Android (Google Play Store)

Here's how you can find your purchase history: 

1. Go to Google Pay and sign in with your Google account.
2. Select the activity/purchase you wish to see the receipt of.
3. Scroll down to see the transaction ID/Google order number. The Google order number looks like this: GPA.1234-1234-1234-12345.

If the purchase has been completed, you should have also received a confirmation email containing this number.

iOS (App Store)

You can find your purchase history in the Settings or Account Settings on your device. Please follow this guide for a more detailed guide.