I do not exactly know how to do it as I have never spent real money on the Internet, but I can suggest you search for it in an app/website of the service/couple of services you used to draw up (is it correct way to refer this action?) a subscription (like Google Pay (service of Google Play), Wallet/iTunes/whether it is named (Apple's service, can find in Settings, App Store and/or iTunes), PayPal, Amazon).
