Solution by Event Log Doctor

This error indicates that the EventSentry agent found no valid license.

Please make sure that a license is present in the following registry key:

HKLM\Software\netikus.net\EventSentry\license

You may try to reinstall the EventSentry agent on that machine using remote update, export the license key on a working machine and reimport it on the machine where this error is logged or contact NETIKUS.NET support.