Seat-based Pricing Implementation Suggestions, i will not promote

I'm just getting out the door with an MVP and have decided to go with seat-based pricing. That said, I am trying to figure out which payment service to go with and how to actually implement it with a focus on simplicity for now. I've worked with Stripe before, but looking at their docs it seems like the seat-based pricing is going to be fairly involved. The only way I can see to do it is to treat it like a usage-based system, and then just send them the number of "uses" (users) before they charge it each month. Seems a bit hacky and involved to me, not to mention all of the corner cases I need to handle with webhooks. I would honestly be ok even with a system where I have to manually go in and put how much to charge them each month and do the payment for the MVP, but for the UX I need something to collect and store their payment information.