Where can I find the receipts?

iTunes:

• If you are using an iOS device, you can find the receipt by logging into your iTunes account and selecting "Purchase History".
• If the purchase were made more than 90 days ago, please follow the steps provided in the following link: https://support.apple.com/en-us/HT204088 to locate the receipt. 

Google Play:

• If you are using an Android device, you can find the receipt by searching for “Google checkout” in the email you use with Google Play.