Where do I find my purchase history?

iOS

1. Open iTunes on your computer
2. Click 'Sign In', and then enter the Apple ID and password that you used to make the purchase
3. Click your name and select 'Account Info' from the menu
4. Enter your password again
5. Scroll down to 'Purchase History'
6. click 'See All' 

Google Play

1. Go topayments.google.com, and log in with the account you wish to see the purchase history for
2. Select 'Transactions' and this will show you your purchase history
3. Selecting an item from the list should show you the receipt for that individual purchases