anisur Speaking from experience, The more you add the more can go wrong in terms of changes on Enhance side, especially when you consider the relative young age of the software! If they decide v13 api is a total rewrite - that could cause havoc for all billing integrations!
We've added SSO, resource usage and a few other bits like supporting the subscription only mode, fields for easier migration from other billing platforms alongside a good way to handle location filtering on sign up and it's probably one of our more popular modules. Infact it's been a while since we've had any feature requests for it to be honest!
It would absolutely be possible for Blesta, would people actually want it that way? I highly doubt it if I'm honest!