The warning is displayed in Plesk:
Warning: You are currently operating within the grace period of your product license. To update your product license, select the Retrieve Keys option on the License Management page.
Manual renewal of the license key works fine at Tools&Settings > License Management > Retrieve Keys .
/usr/local/psa/admin/logs/panel.log the following error appears:
2014-05-11T06:23:23+02:00 ERR (3) [panel]: KeyUpdate Result code: 2 Network failure
2014-05-11T06:23:23+02:00 ERR (3) [panel]: KeyUpdate Result desc: Unable to connect to license server https://ka.plesk.com:5224/xmlrpc.
cURL error description: Couldn't connect to server(7)
This message may appear for a short period of time if grace period already started, but Daily Maintenance script is not yet executed or failed and the license key is not updated yet. The grace period does not limit any functionality and Customers of Plesk will not see this warning.
The message appears when
ka.plesk.com already generated new license keys, but Plesk server did not retrieve the new keys yet because of the time difference between ka.plesk.com and the Time Zone of the server Plesk is installed to.
This issue is considered a software issue #PPPM-1796 and will be fixed in future product updates.
As soon as DailyMaintenance task is finished, the issue should be resolved. DailyMaintenance task runs on a daily basis.