What the OP fails to explain is how we can ensure that the user pays for the used service. The problem is that we have to bill after the service usage and the user could run away without paying and create a new account for his next use of the service.
That’s the reason of upfront payment and the bucket usage payment model. An alternative would to pay upfront for a credit of usage, but this would require to monitor the usage and an action when the credit falls below a threshold.
The model to use depends on the type service we offer. If we can afford the loss due to people running away without paying the service, then it’s ok to bill after use. But that wouldn’t be a great business model.
To me, the upfront payment of a usage credit seam the best compromise.
I think the credit-based system is the best compromise. It's even better if the cusomer can explicitly opt into an automatic top-up option, where they're automatically billed when their balance falls below a certain threshold. This is even better than the bucket model, as those who want their service running at all times won't risk running out of what their bucket offers, whereas those who don't want to control how much they spend can do the top ups manually.
Another point in favour of this model: as the business is in control of the credit, they can implement custom flows of this virtual money bag without hitting any charges. Famous example being the $20 offered when signing up on some hosting services, or referral programs.
It depends on the type of service, setting up new accounts to dodge charges can be very annoying if there's any kind of data to move around, and it would be easy to spot for the service provider.
That’s the reason of upfront payment and the bucket usage payment model. An alternative would to pay upfront for a credit of usage, but this would require to monitor the usage and an action when the credit falls below a threshold.
The model to use depends on the type service we offer. If we can afford the loss due to people running away without paying the service, then it’s ok to bill after use. But that wouldn’t be a great business model.
To me, the upfront payment of a usage credit seam the best compromise.