(NOTE: NX versions prior to 5.1 are not supported on Windows 7)

Unable to revoke a license installed on Windows 7 using an unsupported License Management Utility.  License was previously installed on an OS that the non-Windows 7 compatible License Management Utility was installed on.

From the License Management utility, go to Start Menu > All Programs > Micro Focus Net Express X.X > Configuration > Right-click "License Management System" > Choose "Properties".  Under the Compatibility tab, check the box for "Run this Program in Compatibility Mode for:" and select the previous version of OS that you were running.