To retrieve the Plesk license key currently installed on a server, use the get operation with the key parameter specified.
A request XML packet getting license key contains the key node nested within the get operational node:
<packet version="1.4.2.0">
<server>
<get>
<key/>
</get>
</server>
</packet>
For information on the response packet structure and response samples, refer to the Getting Server Information: License Key section.