Yep..you simply do this from inside the plesk cp...
see the instructions at sw-soft's site:
http://download1.sw-soft.com/Plesk/Plesk7....ml/ch03s66.html
>>>>>>>>>> (this is the section you are looking for)
Managing Additional License Keys
Additional keys are license keys for add-ons (additional features for your Plesk), such as site applications and Dr.Web antivirus program which are not included in the basic Plesk license key.
To access the additional license keys management functions, on the License management page, click the Additional License Keys tab.
To retrieve the ordered additional key, click the Retrieve Keys icon. Plesk will retrieve the license key and automatically upload it to your control panel.
To manually upload the desired additional license key file from your local machine to your Plesk control panel, click the Upload Key icon. You will be taken to the page where you will be asked to specify the path to the license key file location.
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