diff --git a/packages/in_app_purchase/in_app_purchase/CHANGELOG.md b/packages/in_app_purchase/in_app_purchase/CHANGELOG.md
index 4609d6cf30b6..6e6a17cbc222 100644
--- a/packages/in_app_purchase/in_app_purchase/CHANGELOG.md
+++ b/packages/in_app_purchase/in_app_purchase/CHANGELOG.md
@@ -1,10 +1,11 @@
-## NEXT
+## 3.2.4
 
 * Updates minimum supported SDK version to Flutter 3.35/Dart 3.9.
 * Updates README to reflect currently supported OS versions for the latest
   versions of the endorsed platform implementations.
   * Applications built with older versions of Flutter will continue to
     use compatible versions of the platform implementations.
+* Clarifies `completePurchase` usage and the consequences of unfinished transactions in the README and docstrings.
 
 ## 3.2.3
 * Updates minimum `in_app_purchase_storekit` version to 0.4.0.
diff --git a/packages/in_app_purchase/in_app_purchase/README.md b/packages/in_app_purchase/in_app_purchase/README.md
index 79b870145493..8f3b1c9cdcaa 100644
--- a/packages/in_app_purchase/in_app_purchase/README.md
+++ b/packages/in_app_purchase/in_app_purchase/README.md
@@ -48,6 +48,8 @@ can start using the plugin. Two basic options are available:
 
 1. A generic, idiomatic Flutter API: [in_app_purchase](https://pub.dev/documentation/in_app_purchase/latest/in_app_purchase/in_app_purchase-library.html).
    This API supports most use cases for loading and making purchases.
+   
+  > **NOTE**: On iOS and macOS, the generic API uses StoreKit 2 by default. If you need to fall back to StoreKit 1, call `InAppPurchaseStoreKitPlatform.enableStoreKit1()` before registering the platform.
 
 2. Platform-specific Dart APIs: [store_kit_wrappers](https://pub.dev/documentation/in_app_purchase_storekit/latest/store_kit_wrappers/store_kit_wrappers-library.html)
    and [billing_client_wrappers](https://pub.dev/documentation/in_app_purchase_android/latest/billing_client_wrappers/billing_client_wrappers-library.html).
@@ -196,6 +198,24 @@ if (_isConsumable(productDetails)) {
 // Updates will be delivered to the `InAppPurchase.instance.purchaseStream`.
 ```
 
+StoreKit 2 Specific Purchases (iOS/macOS)
+When StoreKit 2 is enabled, you can use Sk2PurchaseParam to include StoreKit 2 specific parameters such as win-back offer identifiers or promotional offers with signatures.
+
+```dart
+import 'package:in_app_purchase_storekit/in_app_purchase_storekit.dart';
+
+final productDetails = ...; // Obtained from queryProductDetails
+
+final purchaseParamSk2 = Sk2PurchaseParam(
+  productDetails: productDetails,
+  winBackOfferId: 'your_win_back_offer_id',
+);
+
+await InAppPurchase.instance.buyNonConsumable(
+  purchaseParam: purchaseParamSk2,
+);
+```
+
 ### Completing a purchase
 
 The `InAppPurchase.purchaseStream` will send purchase updates after initiating
@@ -209,7 +229,9 @@ purchase and the store can proceed to finalize the transaction and bill
 the end user's payment account.
 
 > **Warning:** Failure to call `InAppPurchase.completePurchase` and
-> get a successful response within 3 days of the purchase will result a refund.
+> get a successful response within 3 days of the purchase will result in a refund on Android. On iOS/macOS (using StoreKit 1 or StoreKit 2), failing to complete purchases causes the transactions to remain in Apple's unfinished transaction queue, which has two major side effects:
+> 1. The transactions will be repeatedly re-delivered on the `purchaseStream` on every app launch.
+> 2. Any subsequent attempt to purchase the same product ID will immediately fail with an error indicating a duplicate transaction is pending.
 
 ### Upgrading or downgrading an existing in-app subscription
 
diff --git a/packages/in_app_purchase/in_app_purchase/lib/in_app_purchase.dart b/packages/in_app_purchase/in_app_purchase/lib/in_app_purchase.dart
index 4bc5f9142200..d518ca4224cc 100644
--- a/packages/in_app_purchase/in_app_purchase/lib/in_app_purchase.dart
+++ b/packages/in_app_purchase/in_app_purchase/lib/in_app_purchase.dart
@@ -173,6 +173,14 @@ class InAppPurchase implements InAppPurchasePlatformAdditionProvider {
   /// For convenience, [PurchaseDetails.pendingCompletePurchase] indicates if a
   /// purchase is pending for completion.
   ///
+  /// iOS/macOS Warning:
+  /// If you do not call [completePurchase] for a transaction, that transaction
+  /// will remain in Apple's unfinished transaction queue. This has two consequences:
+  /// 1. The transaction will be repeatedly re-delivered on the [purchaseStream]
+  ///    every time the app is restarted.
+  /// 2. Any subsequent attempts to buy the same product ID will fail with a purchase
+  ///    error indicating a duplicate transaction is pending.
+  ///
   /// The method will throw a [PurchaseException] when the purchase could not be
   /// finished. Depending on the [PurchaseException.errorCode] the developer
   /// should try to complete the purchase via this method again, or retry the
diff --git a/packages/in_app_purchase/in_app_purchase/pubspec.yaml b/packages/in_app_purchase/in_app_purchase/pubspec.yaml
index 6d8a8cf99f23..4742be41c839 100644
--- a/packages/in_app_purchase/in_app_purchase/pubspec.yaml
+++ b/packages/in_app_purchase/in_app_purchase/pubspec.yaml
@@ -2,7 +2,7 @@ name: in_app_purchase
 description: A Flutter plugin for in-app purchases. Exposes APIs for making in-app purchases through the App Store and Google Play.
 repository: https://github.com/flutter/packages/tree/main/packages/in_app_purchase/in_app_purchase
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+in_app_purchase%22
-version: 3.2.3
+version: 3.2.4
 
 environment:
   sdk: ^3.9.0
diff --git a/packages/in_app_purchase/in_app_purchase_platform_interface/CHANGELOG.md b/packages/in_app_purchase/in_app_purchase_platform_interface/CHANGELOG.md
index 7468310ea497..775474f40e77 100644
--- a/packages/in_app_purchase/in_app_purchase_platform_interface/CHANGELOG.md
+++ b/packages/in_app_purchase/in_app_purchase_platform_interface/CHANGELOG.md
@@ -1,6 +1,7 @@
-## NEXT
+## 1.4.1
 
 * Updates minimum supported SDK version to Flutter 3.35/Dart 3.9.
+* Clarifies `completePurchase` usage and the consequences of unfinished transactions in the README and docstrings.
 
 ## 1.4.0
 
diff --git a/packages/in_app_purchase/in_app_purchase_platform_interface/lib/src/in_app_purchase_platform.dart b/packages/in_app_purchase/in_app_purchase_platform_interface/lib/src/in_app_purchase_platform.dart
index eac2a80e214f..fb293482f7e9 100644
--- a/packages/in_app_purchase/in_app_purchase_platform_interface/lib/src/in_app_purchase_platform.dart
+++ b/packages/in_app_purchase/in_app_purchase_platform_interface/lib/src/in_app_purchase_platform.dart
@@ -161,6 +161,14 @@ abstract class InAppPurchasePlatform extends PlatformInterface {
   /// For convenience, [PurchaseDetails.pendingCompletePurchase] indicates if a
   /// purchase is pending for completion.
   ///
+  /// **iOS/macOS Warning:**
+  /// If you do not call [completePurchase] for a transaction, that transaction
+  /// will remain in Apple's unfinished transaction queue. This has two consequences:
+  /// 1. The transaction will be repeatedly re-delivered on the [purchaseStream]
+  ///    every time the app is restarted.
+  /// 2. Any subsequent attempts to buy the same product ID will fail with a purchase
+  ///    error indicating a duplicate transaction is pending.
+  ///
   /// The method will throw a [PurchaseException] when the purchase could not be
   /// finished. Depending on the [PurchaseException.errorCode] the developer
   /// should try to complete the purchase via this method again, or retry the
diff --git a/packages/in_app_purchase/in_app_purchase_platform_interface/pubspec.yaml b/packages/in_app_purchase/in_app_purchase_platform_interface/pubspec.yaml
index 4ebb53da84cc..d4660a55e979 100644
--- a/packages/in_app_purchase/in_app_purchase_platform_interface/pubspec.yaml
+++ b/packages/in_app_purchase/in_app_purchase_platform_interface/pubspec.yaml
@@ -4,7 +4,7 @@ repository: https://github.com/flutter/packages/tree/main/packages/in_app_purcha
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+in_app_purchase%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 1.4.0
+version: 1.4.1
 
 environment:
   sdk: ^3.9.0
diff --git a/packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md b/packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md
index 1d56456408e0..c2c00546bd73 100644
--- a/packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md
+++ b/packages/in_app_purchase/in_app_purchase_storekit/CHANGELOG.md
@@ -1,6 +1,12 @@
+## 0.4.8+2
+
+* Clarifies `completePurchase` usage and the consequences of unfinished transactions in the README and API docstrings.
+* Prevents duplicate purchase attempts in StoreKit 2 by throwing a `storekit_duplicate_product_object` error when a product already has an unfinished transaction.
+
 ## 0.4.8+1
 
 * Fixes StoreKit 2 purchase flow to send cancelled/pending/unverified results to `purchaseStream`.
+
 ## 0.4.8
 
 * Fixes an issue causing StoreKit2 purchases to be reported as `restored` and left in an
diff --git a/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/InAppPurchasePlugin+StoreKit2.swift b/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/InAppPurchasePlugin+StoreKit2.swift
index 3b4ceac802c8..dd5db6a3342a 100644
--- a/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/InAppPurchasePlugin+StoreKit2.swift
+++ b/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit/StoreKit2/InAppPurchasePlugin+StoreKit2.swift
@@ -85,6 +85,22 @@ extension InAppPurchasePlugin: InAppPurchase2API {
           }
         }
 
+        for await verificationResult in Transaction.unfinished {
+          switch verificationResult {
+          case .verified(let transaction):
+            if transaction.productID == id {
+              let error = PigeonError(
+                code: "storekit_duplicate_product_object",
+                message:
+                  "There is a pending transaction for the same product identifier. Please either wait for it to be finished or finish it manually using `completePurchase` to avoid edge cases.",
+                details: id)
+              return completion(.failure(error))
+            }
+          case .unverified:
+            break
+          }
+        }
+
         let result = try await product.purchase(options: purchaseOptions)
 
         switch result {
diff --git a/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit_objc/messages.g.m b/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit_objc/messages.g.m
index 7be9e75eb517..ae7ef1937a2e 100644
--- a/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit_objc/messages.g.m
+++ b/packages/in_app_purchase/in_app_purchase_storekit/darwin/in_app_purchase_storekit/Sources/in_app_purchase_storekit_objc/messages.g.m
@@ -733,11 +733,11 @@ void SetUpFIAInAppPurchaseAPIWithSuffix(id<FlutterBinaryMessenger> binaryMesseng
         binaryMessenger:binaryMessenger
                   codec:FIAGetMessagesCodec()];
     if (api) {
-      NSCAssert([api respondsToSelector:@selector(startProductRequestProductIdentifiers:
-                                                                             completion:)],
-                @"FIAInAppPurchaseAPI api (%@) doesn't respond to "
-                @"@selector(startProductRequestProductIdentifiers:completion:)",
-                api);
+      NSCAssert(
+          [api respondsToSelector:@selector(startProductRequestProductIdentifiers:completion:)],
+          @"FIAInAppPurchaseAPI api (%@) doesn't respond to "
+          @"@selector(startProductRequestProductIdentifiers:completion:)",
+          api);
       [channel setMessageHandler:^(id _Nullable message, FlutterReply callback) {
         NSArray<id> *args = message;
         NSArray<NSString *> *arg_productIdentifiers = GetNullableObjectAtIndex(args, 0);
diff --git a/packages/in_app_purchase/in_app_purchase_storekit/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme b/packages/in_app_purchase/in_app_purchase_storekit/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme
index a65139025b00..d9fb4e2662c8 100644
--- a/packages/in_app_purchase/in_app_purchase_storekit/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme
+++ b/packages/in_app_purchase/in_app_purchase_storekit/example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme
@@ -44,6 +44,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      customLLDBInitFile = "$(SRCROOT)/Flutter/ephemeral/flutter_lldbinit"
       shouldUseLaunchSchemeArgsEnv = "YES"
       codeCoverageEnabled = "YES">
       <MacroExpansion>
@@ -73,6 +74,7 @@
       buildConfiguration = "Debug"
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      customLLDBInitFile = "$(SRCROOT)/Flutter/ephemeral/flutter_lldbinit"
       launchStyle = "0"
       useCustomWorkingDirectory = "NO"
       ignoresPersistentStateOnLaunch = "NO"
diff --git a/packages/in_app_purchase/in_app_purchase_storekit/example/shared/RunnerTests/InAppPurchaseStoreKit2PluginTests.swift b/packages/in_app_purchase/in_app_purchase_storekit/example/shared/RunnerTests/InAppPurchaseStoreKit2PluginTests.swift
index 6440b374e41b..0a899b575c9f 100644
--- a/packages/in_app_purchase/in_app_purchase_storekit/example/shared/RunnerTests/InAppPurchaseStoreKit2PluginTests.swift
+++ b/packages/in_app_purchase/in_app_purchase_storekit/example/shared/RunnerTests/InAppPurchaseStoreKit2PluginTests.swift
@@ -547,4 +547,31 @@ final class InAppPurchase2PluginTests: XCTestCase {
     await fulfillment(of: [expectation], timeout: 5)
   }
 
+  func testDuplicatePurchaseFails() async throws {
+    let firstPurchaseExpectation = self.expectation(description: "First purchase should succeed")
+    let secondPurchaseExpectation = self.expectation(description: "Second purchase should fail")
+
+    plugin.purchase(id: "consumable", options: nil) { result in
+      switch result {
+      case .success:
+        firstPurchaseExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("First purchase should NOT fail. Failed with \(error)")
+      }
+    }
+    await fulfillment(of: [firstPurchaseExpectation], timeout: 5)
+
+    plugin.purchase(id: "consumable", options: nil) { result in
+      switch result {
+      case .success:
+        XCTFail("Second purchase should NOT succeed because a transaction is already pending.")
+      case .failure(let error as PigeonError):
+        XCTAssertEqual(error.code, "storekit_duplicate_product_object")
+        secondPurchaseExpectation.fulfill()
+      case .failure(let error):
+        XCTFail("Unexpected error type: \(error)")
+      }
+    }
+    await fulfillment(of: [secondPurchaseExpectation], timeout: 5)
+  }
 }
diff --git a/packages/in_app_purchase/in_app_purchase_storekit/pubspec.yaml b/packages/in_app_purchase/in_app_purchase_storekit/pubspec.yaml
index abc167b353bb..61b5cdfd5cb5 100644
--- a/packages/in_app_purchase/in_app_purchase_storekit/pubspec.yaml
+++ b/packages/in_app_purchase/in_app_purchase_storekit/pubspec.yaml
@@ -2,7 +2,7 @@ name: in_app_purchase_storekit
 description: An implementation for the iOS and macOS platforms of the Flutter `in_app_purchase` plugin. This uses the StoreKit Framework.
 repository: https://github.com/flutter/packages/tree/main/packages/in_app_purchase/in_app_purchase_storekit
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+in_app_purchase%22
-version: 0.4.8+1
+version: 0.4.8+2
 
 environment:
   sdk: ^3.9.0