Another option (which has since been added to that page) is:
.:: The configuration of PHP on your server has changed.
The licensed key depends on some functions of PHP to work correctly. A change in the features enabled in PHP could cause the license key to be disabled (this could be do to a recent upgrade of PHP). If the license key needs to be updated because of this, please submit a License Reset Request.
Either way, you would still need to use the form to request a new license key.