How to connect a payment system to the form on ios and android?

Question

Mobile development

I bought the application on the market, it showed itself very well in work. Now you need to connect a payment system (any) to the ad submission form, with a fixed price, I think that is a very trivial task. A question for the community is what you need to know in general when connecting via API or in another way to the application, and in particular to find a freelancer for such a task, and what are the rules for the app store and play market?

Answer 1

I think it's a very trivial task.

and in particular to find a freelancer for such a task

Good luck! Rules and nuances - SEA!

what are the rules for the app store and play market

Have you been banned everywhere and not allowed to read the rules?)