1. Log in to the Client Area, then login with your email address and password.
2. Click "Service" and "My Service",
3. It will display your Products and services window, click on your Plesk License code, for example Plesk Web Admin 10 Domain for Dedicated Server.
4. Scroll down the webpage until you see "License Details".
Product Key will be displayed. Enter this key code to activate your Plesk Control Panel
For example A00B00-xxxxxx-xxxxxxx-xxxxx-xxxxxx
It looks like below
