This can happen if you exceed your allotment of licenses. Note that, Teramind Cloud is licensed per user whereas Teramind On-Premise/Private Cloud are licensed per endpoint (computer).
Also, note that, The Hidden Agent will create a new employee account for each logged on user, which have to be licensed separately for the Cloud accounts. Similarly, if the same user logs in from different computers, you will need separate licenses for the On-Premise/Private Cloud deployments. Check out the following articles to learn how to solve this issue: