If you didn't get an email with the payment receipt and transaction number, you can check it as follows:
For iOS devices:
- Select Settings > [your name] > iTunes Store and App Store.
- Tap your Apple ID and select View Apple ID. You may need to sign in using your Apple ID.
- Swipe up to the “Purchase History” section and tap it.
- Press the > icon to the right of the final invoice to view invoice details, including invoice date and order code.
For Android devices:
- Go to pay.google.com.
- Select "Other Purchases".
- Tap "View Purchases".
- Select your order to open the confirmation.
Follow the link for more information.