Watch out for FLEECEWARE - Mobile apps that can still charge users even after users uninstall the app from their devices. Researchers have identified 32 iOS apps (see table at the end of this article) that charge up to $30/month or $9/week for simple features that are usually available for free. Some of these fees seem small, but they can add up to between $360 and $468 per year.

https://www.zdnet.com/article/fleeceware-apps-discovered-on-the-ios-app-store/