Asking about payment method.

I want to build an app as follow:

  1. Users can buy/sell your products directly
  2. When users buy a product from other user, he/she has to use points inside the app
  3. When the points of a user reach to a pre-defined amount, he/she can withdraw to real money (ex: USD)
  4. The points use in the app can be bought in the app (or outside the app)

My question is: When user buy the points, what payment method the app should support? Can we implement payment method using credit card in the app to support user buy points?

Asking about payment method.
 
 
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