Let's say your license limits you to
10 concurrent CMS users at once. If someone's user account is in the
Sitecore Client Users role, and they log in with that account, do they count as a concurrent CMS user who occupies one of those 10 spots?
From the Sitecore documentation:
Sitecore Client Users
Gives the user minimal access to Sitecore. With this role, the user can log in to the Sitecore Desktop, but will not have access to any applications.
All of the other Sitecore client roles are members of the Sitecore Client Users role, which means that users in any Sitecore client role are automatically members of the Sitecore Client Users role.