Hi @ravisagar ,
As of today, per user pricing is the only pricing model available. Other options were discussed in RFC-60, but none of those has landed yet.
If you are planning to launch a Forge app on the marketplace, you should be aware of the potential infrastructure costs and price or budget accordingly. While this is very visible with Forge and its FaaS architecture, the general concept is not entirely new – you should plan your pricing in such a way that it will at the very least cover the expected infrastructure cost.
Someone from Atlassian will be better suited to answer your last question, but I fully expect that we would be charged for an app that only is deployed to dev and still exceeds the platform limits. Not that I believe we would ever reach those limits purely during development.