What are the payment options if you want to add payment feature on your F7 app? PayPal? and how to do it?
You can try Cordova Plugin Purchase which supports Google/Apple Pay for virtual items inside the app or turn the free version to a pro once payment is verified.
Alternatively, you can use PayPal or Stripe API. You will have to handle logic on your back end. For example, Stripe has libraries for all major languages.