As far as I know, an app should use an In-app purchase to unlock premium content, features, or levels, etc. Apple won't allow making payments via third-party payment gateways or even providing a link to do payment other than in-app purchase is against the guidelines.
Today I found an app in AppStore where they use a third-party payment gateway to unlock their premium content.
Attaching the screenshot
Here they are asking for credit card details and entering the card details completes their payments process (Worth mentioning they have cool UX for this!).
I am wondering how did they manage to get into the store? or did apple update the policies? or is it a new feature?
I am clueless. Any help is greatly appreciated.