Non-Renewing Subscription multiple Times

Hi,

I am new at adding in-app purchases / subscriptions to my app.

I am making a fitness app, where users can join multiple challenges.

apple is not letting us implement 3rd party payment system for users to join challenge, so i need to do IAP in my app.

I am bit confused which one i choose,
In app, a user can join a challenge for specific time (i.e. 30 days, 1 week, 2 week) period the time is depending on a challenge which is created by nutritionists, but a user can also join another challenge at a time.

lets say for example,
there are 2 challenges available right now
  1. 30 days daily workout challenge

  2. 30 days weight loss diet challenge

both challenges have the same price.

I have made in app purchase called 'challenge 13.99' (product price in IAP is 13.99 USD).

whenever user jones the 1st challenge they buy for productID 'challenge 13.99'.

now I want to join 2nd challenge as well, so now will i get something like 'user already subscribe to this product' from the apple server or let me buy same product again?
If it is a non-renewing subscription, user can buy the same product again and again. Your app will need to check whether the user is still within the particular challenge period (within 30 days after buying the daily workout challenge), so that they wont accidentally buy the same challenge again while still inside the 30 days period.
Non-Renewing Subscription multiple Times
 
 
Q