are in game payments / freemium model possible?

If you consider any "social freemium" game like bingobash, candy crush, world of tanks etc, they all allow the player to purchase in game coins and powerups. There is no monetary prize, so they dont require gaming licenses which a casino type game would

The question is what options would be available for a C2 game? I can't find any C2 documentation on any APIs or similar which would be exposed by the built in wrappers such as appmobi, cocoon or phone gap.

I already have a full server side implementation, just no payment system. I presume that apple would not allow me to put a paypal similar interface into a ios app.

If I want a browser version f the game, are there any in game payment options, or would I need to integrate with datacash or myriad or similar, get my own merchant account, and do it all by hand outside the game in a website? Putting up dialogs or switching to other layouts from the game is non trivial in C2, so I try to avoid it (dialogs allow buttons underneath to still work, and switching layouts loses state).

Any thoughts on how to do in game payments appreciated.

How about Clay.io api ?

I checked out clay.io, but I already have my own player database, league tables etc. The clay.io puts strange popups in the top right hand corner of the app. I would rather use the native ios and android payment systems if there is an api for this, if not I guess I have to write my own or try and integrate with phone gap or app mobile, both of which I have the same problem that I don't want 90% of their functionality or use database.