A scenario where this may occur is if Software Maintenance Service was not renewed for some seats of a product. Before you make these changes, you will need to modify the "asset_info" tag in the license file as well. Add the release at the end of the "asset info" tag in the license file. For this example there are 5 seats of MATLAB for R2017a and 2 for R2016b. Modify your options file with the following:
GROUP ml_users_R2017a user1 user2 user3 user4 user5
GROUP ml_users_R2016b user1 user2
INCLUDE MATLAB:Asset_info=999999_R2017a GROUP ml_users_R2017a
INCLUDE MATLAB:Asset_info=999999_R2016b GROUP ml_users_R2016b
Afterwards, you must stop and restart your license manager for these changes to take effect.
For more information about how to use asset_info in your options file, see related solution 1-5WB4Y9: "What is the asset_info tag in my license file?"