monthly - background payment with Stripe

[kekko7072]

Hey,
How can I implement payment on background (on firebase function) using the customer id with a registered card.

1. Is it possible?
2. What is the flow?
3. there are any API I can follow?

I am trying to make a service app (like bike sharing) and as payment I want to make a monthly payment based on how much you used the service.
It's like a subscription but with variable amount to pay. I will run it on firebase functions. Any idea or suggestion?
Thankyou so much!