[syrrim]

Not being familiar with these things, why not just emulate "upgrades" through in app purchases? You would offer a limited version of the app for free, and then prompt users to pay for the full version. Every now and then, you would declare a new version of the app, and only give access to new features you add to relatively recent users. Older users would be prompted to pay (again via iap) a reduced price to get the "upgrade".

Issues with this are:

- still has the 30% fee instead of 15%

- adds complexity, due to needing to track what each feature is, and which users are allowed to access each feature

- to obviate above, you would probably end up giving all bugfixes/optimizations/etc to old features to all users.

Could maybe clear up the first point by accepting payment via subscription instead, with the following caveat: "if you stay subscribed for more than 3 years [say], you will gain permanent access to the app, minus any features added after you terminate your subscription". As a user, I would feel pretty good about that (i think), since I'm not locked into either a subscription or a full payment. Of course, this is likely a downside for whoever makes the app, since it probably entails less revenue for them.