Go to your Rhino account. Set up a Team, add your licenses to the Team and then invite users to your Team.
To see what users are using your licenses, pick Cloud Zoo Teams and Licenses
Usage Bar will show how many user have a license in use.
With License chains of Rhino 6, 7, or 8, checking out one version will show usage for all the licenses in the chain. They are linked or chained together.