Answer

Problem

The license key is reported as invalid in the post install wizard or on the licensing page and is not saved.
Product updates do not function
Product does not filter URLs or scan downloads
License key accepted by the product and the product works for some time. After a while it ceases to receive updates or deliver its functionality. The Settings >Security > Security Engines page shows that all AV engines are not licensed and the licensing page shows "Invalid license key".

Verify that you are using the GFI WebMonitor license key that matches the version you are installing. You can verify this by checking the license at the customer portal. http://Customers.gfi.com . If you are upgrading from previous version you need to upgrade the previous license key from the customers area or by contacting the Sales department.
Re-register the product using the GFI WebMonitor license key and allow the services to restart. GFI WebMonitor - Management Console > Settings > General > Licensing. Paste the license key in and select Update License.
If you are still having issues with the license key, re-run the post installation wizard and re-enter the license key. GFI WebMonitor - Management Console > Settings> Configuration Wizard.
If the issue persists please open a support ticket. http://gfi.com/support/technical-support-form

You are using license key for another version; Resolution: Please make sure you provide a valid license key for the actual version. Customers upgrading from previous versions need to obtain a new license key from the customer area or by contacting our sales department.
Customers performing a clean install should have the license key pre-filled in the appropriate field when running the Post Install Wizard. In case it is not, please enter the license key received via email after the website registration process.
There may be a problem in the post-validation licensing key verification performed periodically by the product.