Thanks! We cover all types of SaaS companies' billing. We often say that if you can track it, we can bill it! We cover subscriptions, hybrid, pay-as-you-go, and per-seat pricing models.
We believe that the future of billing is hybrid - a mix of all the above. We've seen many missed revenue opportunities from companies that weren't able to price overage on top of a per-seat or pure subscription pricing (often because it was too hard to build, either internally or with existing vendors)