Need suggestions for database & versioning

Hello everyone,

I am currently on the search for a solution to our growing need for more development versions. We are currently running on the professional plan, however, the explanation for versioning when concerning databases is a bit confusing to me.

We currently need three/four versions One live, one development, one demo, and one sandbox.
The question i’ve been trying to get answered is whether or not each of my development versions has their own database. Currently, I only see it working as one live database and one development database. Does this mean if I use the production plan I would have to share one database between 10+ development versions?

We would like to have a separate database for each, one solution we’ve brainstormed is using two professional plans and exporting/importing the application/database as needed to the demo/sandbox application while leaving the Live/Dev versions on the original and separate app.

Any suggestions are very much appreciated. If I wasn’t clear with information, please let me know so I can make edits and make this easier to understand.

Thanks c: