Concurrent meetings

Hey Guys,

Say I want to make an app that facilitates some sort of consulting sessions between a host and a few others. The problem is that I don't know at each time how many such meetings are required concurrently. At some points there is none, but the pick can go as high as 5 concurrent sessions, or even more. Should I buy 5 subscriptions to accommodate the pick? If yes that's really not making sense. Is there any workaround?