There are many different error messages that could be displayed within Plesk based upon the issue that is occurring. For example, if you upload a key that is intended for another version of Plesk Panel you might get one of the errors outlined below.
Plesk License Error #1:
The license key is invalid. In order to use the Panel, please obtain and install a new valid license key. Your license key has expired. To continue using your Panel, you must purchase a non-expiring commercial license key.
Plesk License Error #2:
The license key is invalid. In order to use the Panel, you need to obtain and install a new valid license key. The license key is intended only for use with Parallels Panel operating inside a Xen virtual environment.
To resolve the errors outlined above, we strongly recommend getting in contact with the LicenseCube support team for additional assistance on this issues. To do this, please see the step-by-step directions outlined below:
Should you have any further questions pertaining to your Plesk license, please feel free to get in contact with our web hosting support team for additional assistance.
Article Number: 154
Posted: Tue, May 15, 2012
Last Updated: Wed, May 16, 2012
Posted: LicenseCube Support [firstname.lastname@example.org]
Online URL: http://kbase.licensecube.com/control-panel-licenses/why-does-parallels-plesk-give-me-an-invalid-license-key-error.html