It looks like there may be a way described in the user guide on page 121. I tried to copy the section over, but it just becomes difficult to read in a forum post. [URL]
Is there a way to increase the number of current user sessions to OME 3.2.1? We get a "Unable to log in as the maximum number of sessions has been reached" after there are more than 6 sessions connected.  
Increase number of concurrent user sessions