You are at considerable risk on the iOS App Store. You are making people buy (or download for free) an app because they think it has certain features, and then after two months they discover that you have cheated them because it doesn't have those features at all. If Apple see it this way, they will not allow you to sell the app.
You don't say why you want to leave users stranded after two months. Possibly you are thinking of some sort of subscription scheme, or in-app purchases.
Here is a way to do the same thing, which is not dishonest to the user. I know that it has been accepted by Apple at least once, though of course I'm not in a position to make promises.
- Create an app which is complete, usable, and worth buying or downloading on its own merits; and which does not suddenly start working less well (or stop working altogether) on some date in the future.
- Include with that app a free (time-limited) preview of certain extra features.
The key is that 1, on its own, makes a worthwhile app. You have to make sure that your app description has "includes a free preview of..." before describing your time-limited extra features. It would also be reasonable not to include those extra features in the screenshots, since that would suggest to a customer that the features are part of the app, which they aren't.
This shouldn't mean too large a change in your business model. It is also more respectful of the customers, who pay your wages. And although Google are far more automated than Apple, the same policy will insure you against trouble with them.