In Training Peaks Payments (Early Access) we have the option to Automatically Connect Athlete if they subscribe to 1 of many products we create, however,

have the app look at the groups we created like (My Athletes) and if we create a group of athletes named One Time Service then any new athlete will be connected in that group and help us manage our customers appropriately.

Auto connect and assign the group to the product they purchased.
Subscription Product 1 = Group 1
Sprint Triathlon Product = Sprint Tri Group

If the customer is just added, we will have no idea what product they bought and have to find and dig for the information.

group the customer to the product