This error message is displayed if you have upgraded to a new major version or downloaded an upgrade from the Redgate website which reverts to trial mode. If you have a license and you run into this error you will need to activate your serial key within the tool. You can do this one of two ways depending on the product:
On the Help menu, select Manage my license.
On the Help menu, select Enter serial number
This will put you back into licensed mode.