User license types and count?

Dear Experts,

I have a query regarding user licenses type and count in Production system.

In Production system, we have 100 licenses, but apart from the user count I have observed that there are 3/4 user IDS consuming the license.

I need some information on these users, like are these users always exist and consume the license?

If Yes, then what should be the License type.

Users are below:

BASIS (License = Professiona)

DDIC  (License =TEST)

FINBTR@PRD (i.e. SID)  (License = Blank)

Implementation Vendor ID in PRD (License = Professional)

Thanks,

Garry

PS: Points will be awarded.