Register eLicenser / software Issue

hello there,
when trying the register my key license at “my stienberg” it says: “This eLicenser number has already been registered by another user.”
i cant find any other user that i have or had logged in with.
Im representing An educational institution and we have here 5 licenses for 5 work stations (computers). 4 of them registered with our regular user.

my goals:

  1. find the missing user
  2. unite the to users to one - delete the other user and register the license on the user that have already the other 4 licenses.
  3. Update all Users to the latest Version on Cubase

thank you,