All the licenses for the feature you requested are in use.
Free up a license and try again.
Keeping an LDRA application GUI open consumes a license.
The license is not returned until all LDRA GUIs are closed on that machine. Using the command line obtains a license at start and then returns the license at the end of each command line call.
You can run the command:
lmutil lmstat -f <FEATURE>
where <FEATURE> is the name of the feature that the error message mentions as having reached the maximum users, this will show how many users are in use. See Useful diagnostic commands for more details on using this command.