> they can submit basically any transaction they want at any time This can be generally be accommodated in my suggested model, they just have to specify upfron

> they can submit basically any transaction they want at any time This can be generally be accommodated in my suggested model, they just have to specify upfront how much & how often they'd want to charge. If the gym membership is 50 bucks a month, then the token has a monthly limit of 50 (or maybe a bit more, to account for potential extras). The token lifetime could be set for the membership duration. > car rentals Get 1 token with your rental fee + a separate token (scoped until car return date + some time to inspect/discover any damage) for the deposit amount?