To prohibit, probably nothing. But payment is required to enter the password from googleaccount or poke the fingerprint (see Appendix playmarket in the settings "require authentication for purchases"). This option applies to all purchases in the market (including in-app).
Again, note that the phone may be alternative stores predefined (for example on the Samsung is an interface extension, in addition to playmarket) or by delivering (of the same type yandeksovsky). Can't guarantee they have the same settings (but in any case there will have to first map to tie to something to buy... and why do you need it?)
By the way, I note that the application can be alternative ways in-app purchases beyond the control of the system (for example, the application Vkontakte allows you to buy stickers to the four ways, only one of which is playmarket). I do not know how resolved I was in the full confidence that in playmarket not by playmarket to pay anything, but Vkontakte 100% provides alternatives (other applications will not say because I do not know)