Your license may suddenly become invalid when you login to the control panel. This has been seen to happen when some virus scanners such as Trend Micro Server Protect quarantine the file ensimlicensing.exe as a possible virus. To fix this problem run the Trend Micro ServerProtect Management Console and click on Scan Result. Either click on Scan Now or Task Scan and you should see the ensimlicensing.exe in the list. Select this file and click Take Action then on the next dialog box you should click Restore. This will put the ensimlicensing.exe file back in its original location. The next action you should take is to exclude the file ensimlicensing.exe from being scanned to avoid this problem. You will find this file in for example C:\Program Files\Ensim\WEBppliance\util.
New ensimlicensing.exe file can be obtained from the location :
You need to download this file on your server and place it in the C:\<Ensim Pro Install Directory>\util directory. Once this is done you will need to restart the virtualhosting service.