Unlike one-time payments, subscription payments allow you to charge the customer on a recurring basis. Plans for subscriptions payments can't be created inside the DepositFix app, but need to be set up in Stripe instead.
If you connected Stripe to DepositFix in test mode, make sure you also enable test mode in Stripe before adding any new subscription products (and vice versa - if you connected Stripe in live mode to DepositFix, add the product in Stripe live mode too).
After you've added a subscription product, it will become available inside the DepositFix form builder. You'll also be able to set up your own recurring revenue model (number of charges), which is especially useful for payments in installments (eg. if you're selling online courses). Recurring payments in Stripe + DepositFix can be combined with one-time payment add-ons, and other sales offers which can either be optional or included in the final price.
All in all, DepositFix is very flexible and can cover many different pricing scenarios.