Maybe not “people” but “person”.
It doesn’t really matter, User, People, Person they are all just entities, you can do with them what you choose, you build it!
If they are registered on your system, then I would have them under User, and you can have a field that holds their status. Depending on what service levels you might offer, you ‘might’ have Prospect, Free, Basic, Bronze, Silver, Gold, Platinum, Rhodium, or whatever!
Why go to the hassle of transferring one user from one type to another, when you can have them all in one place and manage them through a feature set dependant on level.
If your prospect doesn’t come to much, and you want to automatically purge them after a while e.g. stale accounts, you can simply run a periodic scheduled API to wipe them out to keep the db clean.