In the Kerio Control dashboard, go to > Register offline by license file .
A Kerio Control license key is a unique code required to activate and use the software. The license key is usually provided by the software vendor, Kerio Technologies, upon purchase of the product. The key is used to validate the software installation and ensure that the user has obtained the product from an authorized source.
If you need a professional-grade firewall but do not have the budget for a Kerio license, consider these highly respected open-source alternatives: