Don't make adding a payment method mandatory in order to apply nitro credit

I have to keep adding and removing my paypal whenever I want to renew my nitro (I have a friend who gifts it to me every month), and it's just so irritating. The whole point of gifted nitro is that it's FREE, if I want to pay for it monthly then I will, I shouldn't be forced to. It's absolutely ridiculous, simply apply the credit automatically instead of asking for my paypal every time....