You can register OpManager by applying the license file that you receive from ManageEngine. To apply the license, follow the steps given below:
Click on the profile icon (Next to the Settings icon on the top bar).
Click on the Register tab.
Click Browse and choose the license file from the location it is saved.
Click the Register button to apply the license file and close.
Should you encounter any errors when applying the license, contact Support with the license error code.