[IOS] Subscription: Can transactionId differ for the same purchase in react-native-iap

[eden170]

Hi,
I’m currently using react-native-iap ^14.4.46 / Storekit 2

I’d like to ask the community if there are any cases where, for the same subscription purchase, the purchase.transactionId value received from onPurchaseSuccess can be reproduced with a different value within a very short time gap (e.g. 0.3 seconds).

In addition, I see both purchase.transactionId and purchase.originalTransactionIdentifierIOS.
Could someone clarify the difference between these two values?

My understanding is that:
Each purchase should have a unique identifier
For the same subscription purchase, these values should not change

However, I’d like to know:
In which situations these two identifiers can be the same or different
Whether transactionId can change for the same subscription flow
Which identifier is safe to rely on when identifying a subscription purchase (especially on iOS)

Any clarification or official references would be greatly appreciated.

Thank you!

[hyochan]

Based on Apple StoreKit 2 official documentation:

Property	Description
transactionId (= id)	A unique identifier for each individual transaction. A new value is generated for each renewal.
originalTransactionIdentifierIOS (= originalID)	The transaction identifier of the original purchase. Remains the same across all renewals.

Answers to Your Questions

1. Can transactionId have different values within a very short time gap (e.g., 0.3 seconds) for the same subscription purchase?

Yes, it's possible. When a subscription renews, a new transaction is created with a new transactionId. Additionally, purchaseUpdatedListener can be called multiple times in quick succession (e.g., during restoration, synchronization, etc.).

2. When are the two identifiers the same or different?

• Same: On the initial purchase, transactionId === originalTransactionIdentifierIOS
• Different: On subscription renewals - transactionId gets a new value, while originalTransactionIdentifierIOS retains the original purchase value

3. Which identifier is safe to rely on when identifying a subscription purchase?

• Use originalTransactionIdentifierIOS - it remains consistent across the entire subscription chain
• This value is also used for App Store Server API calls

Recommendation

// Use originalTransactionIdentifierIOS to identify a subscription
const subscriptionId = purchase.originalTransactionIdentifierIOS;

// Use transactionId to track individual transactions
const individualTransactionId = purchase.transactionId;

Summary

• Each purchase does have a unique transactionId
• However, for subscriptions, transactionId changes with each renewal
• originalTransactionIdentifierIOS is the stable identifier that links all transactions in a subscription chain together
• For subscription identification purposes, always rely on originalTransactionIdentifierIOS

References

• Apple originalID Documentation
• Apple originalTransactionId Documentation
• Apple Transaction Documentation

[eden170]

Hi, thank you so much for the detailed answer and the official sources!
They were very helpful.

I'd like to clarify one more point if you don't mind. When a subscription renewal payment is successfully completed on the server side (StoreKit 2 for iOS and Google Billing for Android), and the user subsequently opens the app, does the onPurchaseSuccess listener automatically detect the renewed 'purchase' object on both platforms?
Or does this automatic detection only work on iOS, with Android requiring a different approach?

I would greatly appreciate your clarification on this.

Thank you again for your time and help!

[hyochan]

Great follow-up question.

Short answer: No — onPurchaseSuccess should not be relied on to detect subscription renewals on either platform.

iOS (StoreKit 2)

Subscription renewals are completed on the App Store server.
react-native-iap does not guarantee emitting onPurchaseSuccess for renewal events.

For additional context from maintainership and testing:

• If a transaction is not finished (finishTransaction / transaction.finish()),
• iOS may re-deliver that unfinished transaction when the app relaunches or resumes,
• which can result in onPurchaseSuccess being triggered again.

This represents reprocessing a pending/unfinished transaction,
not automatic renewal detection, and should not be relied on as such.

Android (Google Play Billing)

Renewals also occur entirely on the server.
When the user opens the app, onPurchaseSuccess will NOT be triggered for renewals.

Recommended approach (both platforms)

• Use onPurchaseSuccess only for user-initiated purchase flows
• Always call finishTransaction after successful processing
• On app launch or resume, call getAvailablePurchases() to fetch current purchases / entitlements
• Send those results to your backend (e.g. IAPKit) for verification and normalization

  import {verifyPurchaseWithProvider} from 'react-native-iap';
  
  const result = await verifyPurchaseWithProvider({
    provider: 'iapkit',
    iapkit: {
      apiKey: 'your-iapkit-api-key',
      google: { purchaseToken: purchase.purchaseToken },
    },
  });
  

  • https://hyochan.github.io/react-native-iap/docs/examples/subscription-flow#iapkit-server-verification

This avoids relying on implicit renewal events and keeps behavior consistent across iOS and Android.