Is it mandatory to include in-app purchases for my gym membership application, which enables gym members to make their monthly payments conveniently?

Is it mandatory to include in-app purchases for my gym membership application, which enables gym members to make their monthly payments conveniently?

If you sell your membership outside IOS and you need to launch IOS app for your gym membership. Yes, you should provide the way to let your user do a subscription on your application.

Is it mandatory to include in-app purchases for my gym membership application, which enables gym members to make their monthly payments conveniently?
 
 
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