Char customers variables amount without having to submit their credit card details

Is there a way we can regularly charge customers variable amounts using the stripe interface, without them having to submit their credit card details every time?

I can see that we can request a stripe customer be created at form submission, but not how we use this information for subsequent transactions 

Subscriptions would work for regular timing/amount but these are irregular for differing amounts.

That's only possible with the subscriptions. 

Or you can enable payment authorization https://www.jotform.com/help/292-How-to-Enable-Payment-Authorization. So when the customers submit the form, they won't be charged immediately. You will have to charge them manually in your Stripe dashboard. Though, I'm not sure if you are allowed to charge the amount you prefer.