I was randomly thinking about that today from a buyer/user perspective.

As the customer I want all the benefits of a small amount of use, if I end up not utilizing it as expected, so that I don't have to cancel or feel like I wasted money on something that I thought I was going to use but didn't.

At the same time, I want the benefit of being a frequent user if I do take full advantage during a period and get good value from it at full budget. In my head I landed on a hybrid kind of flex pay credit structure.

Each month you pay a small fixed fee that unlocks a pool of rollover credits. Light month? You barely touch the pool and the unused credits slide forward , maybe expire, maybe not, no guilt though. Heavy month?

Burn through your credits and then you’re seamlessly billed per-unit or at a cheaper rate block top-up amount for cheaper unit refills, until you hit a soft cap on needing to pay and everything past that rides free. On day one you get a Lightning invoice for the base fee.

This may not answer your wallet, lightning, invoice, payment mechanics, but in the world of SaaS and micropayments we need to solve this, and this is what I was churning while driving across town.