After you make a purchase on Google Play, a confirmation email with your order information is sent to the Google account you used. The order number will begin with "GPA" followed by a series of numbers, such as GPA.1234-1234-1234-12345.
 
 
You can also find your order information on Google Wallet by following these steps:
If you have additional questions on how to locate your order number, please refer to this Google support link: https://support.google.com/googleplay/answer/2506346?hl=en

If you would like to contact our Support for a purchase issue, please attach a screenshot of your receipt and ensure the date of purchase is visible.
 
If you need help taking a screenshot from your device, please follow instructions found here: https://support.google.com/android/answer/9075928?hl=en