How can I get a receipt for my purchase or renewal?

Purchases made through the App Store are purchases made from Apple, not from the developers that create the apps. When you purchase an app on the App Store, Apple will send a receipt to the email address associated with the Apple ID that made the purchase. To find out which email address the receipt was sent to, open the Settings app, tap on your name in the top left, then the email address will appear on the right side under the Apple ID heading.