google android. How to check a purchase in a mobile application in php?

Question

Google

There is a mobile application. There you can buy a bonus (for example, an unlocked theme). In the case of apple, the client sends me receipt_base64 and I check it via curl at https://sandbox.itunes.apple.com/verifyReceipt
googled how Google Android purchase checks are implemented - as a result, there is no specifics anywhere, but only porridge in my head