To activate Plesk for the purchased number of domains, you must install the key license that is sent to you in an email. Key installation instructions are as follows:
Transfer the key file to the server.
Change to super-user with the su - command.
Access the directory where you transferred the key file.
Execute the key file shell script PLSK.dddddddddd.vvvv.sh: sh ./PLSK.dddddddddd.vvvv.sh
PLSK.dddddddddd.vvvv - where dddddddddd is the key number consisting of ten digits, and vvvv is the key version consisting of four digits.
The script will automatically restart the Plesk server with the new key.