Check for updates greyed out sccm

Suddenly you may have noticed that Check for Updates under \Administration\Overview\Updates and Servicing greyed out in your SCCM environment;

Also, Synchronize Software updates tab missing under \Software Library\Overview\Software Updates\All Software Updates

Also, Latest Configuration Manager update pack is available in the console with status Ready to Install, but all the options are greyed out when right click on the update pack under \Administration\Overview\Updates and Servicing;

If we review the event viewer, we will notice Event ID 1, Critical error as below;
The evaluation version of System Center Configuration Manager that is installed on this computer has expired. To purchase a licensed version of Configuration Manager, contact your reseller. For more information about how to upgrade from the evaluation version to the licensed version, see the TechNet documentation library.

Now, Look at the ribbon on the top of the console, it will be clearly marked as the Evaluation is Expired.

To fix above all, enter the product key or if it is lab like mine, then re-install a new instance of Configuration Manager.