I dont know how Apple handles licensing outside of the App Store. as we all know, they want a piece of the pie. Also, the last time I tried to upload a "demo" style app, it got rejected for the lack of functionality, and the fact that it says Demo in it.
They may force you to use In-App Purchasing through the Apple system to unlock licensing/functionality. But I dont know.
So when doing custom logins, or custom activations of an app outside of the App Store, Not sure how they feel about that in the rules. I am kinda interested in that one myself. There are definitely gray areas here, I know there are apps on there that require logins, you know, like google/facebook/etc. But, Not sure how this entails into licensing/activation.