To install the license key, run from the command line the utility ‘key-writer.exe’ installed with Plesk. It is placed into SWsoft\PLESK\admin\bin folder. The only parameter used is the path to the key file.

For instance, you can copy the key to a folder SWsoft\PLESK\admin\key and use the command: SWsoft\PLESK\admin\bin\key-writer.exe SWsoft\PLESK\admin\key\your_license.key

The utility will install the software key into your system. After installation is completed, a system restart is required.