Android
1. Enter payments.google.com, then log in with your Google account.
2. Select Transactions to display your Play Store order history.
3. Tap an individual entry to view its corresponding receipt.

Amazon
1. Go to Amazon.com.
2. If you are not signed in, sign in with your Amazon ID.
3. Tap "My Orders" in the "Accounts & Lists" menu.
4. To see the details of an order, tap "Order details" under the corresponding order number.