Plesk for Linux/Unix:
Your Plesk license number can be found on the License Management page in the Plesk control panel. Check the "Key number" field. It is also shown in the title bar of the browser window when you are logged into Plesk as the "admin" user.
If the control panel is not accessible, you can log in to the server via SSH and learn the license number with the help of the following command:
Plesk versions 7.x - 8.x:
grep 'Key number' /etc/psa/psa.key
Key number: PLSK.12345678.0000
Plesk version 9.x and higher:
grep 'key-number' /etc/sw/keys/keys/key*
Plesk for Windows:
The license number can be retrieved using either of the following methods:
In Plesk, go to Server , License Management , and view the license number there.
Use this command in the command prompt:
If you want to use PowerShell, perform the following:
PS> [xml]$key = Get-Content "path_to_plesk_directory\\admin\\repository\\keys\\key$key_id"