The old IAP plugin is being replaced with a new plugin soon.
To Save the shear frustration, of lots of C2 users that monetise, and have faithfully upgraded to C3, Like me, Why don't you just Grey out the feature, then with a pop-up just say
......We are working on implementing this feature, We thank you for your patience................
Or something like that, because mobile devs, would have spent many frustrating hours/days, trying to get this to work, without knowing that it doesn't yet, all this frustration could have been avoided in the first place, we know it's in Beta, we just need to know which bits work, and which bits don't.
Cheers, Keep at it.