All in-game purchases are processed by the app store you used to download the game (Google Play/App Store/Huawei AppGallery/Amazon Appstore/Microsoft Store).
 
You can find more information about your purchase history in the customer support section on the Apple, Google, Huawei, Amazon, Microsoft websites.

Apple App Store

Google Play

Huawei AppGallery

Amazon Appstore

Microsoft Store

Note: every time you make a purchase, a receipt is sent to the email address connected to your Google Play/Apple ID/Huawei/Amazon/Microsoft account.