I'm afraid that doesn't make much sense to me. If requiring a one-time paid upgrade after X days is prohibited, why would requiring multiple paid upgrades after X days be allowed?

If you happen to know of any sources for that policy or any examples, I'd be interested in seeing them.

It's possible to offer a free trial as part of an auto-renewable subscription,[1] but that scenario is different to the app ceasing to function X days after you've downloaded it.

[1] https://developer.apple.com/library/ios/documentation/Langua...