Q: how to pay on apple store/apple id without a credit card?

You'll need to buy an iTunes gift card and redeem it to your Apple ID account. Then use that to pay for the subscription.

In the iTunes App, App Store App, iBooks App.  Tap on the "Featured" tab and scroll all the way to the bottom and click on the bottom that says "Redeem"

Redeem and use iTunes Gift Cards and content codes - Apple Support