With some updates and upgrades to windows EnergyGauge will become deactivated and revert back to a trial license where your reports will have a watermark that says "For Demonstration Purposes Only". When this happens you simply need to reactivate using the activation key that was sent to you at the time of purchase. If you do not have your activation key please open a ticket and include either the order number or license owners email address and name then we will look up your activation key. 

To reactivate you will Open EnergyGauge then on the first screen you see, select the Help menu and select License. Click on the Activate/Deactivate License button (a new window will open up, this might take a few seconds to open), click Activate your license then Activate Online. Input your activation key found in the email sent at the time of purchase then click Activate and if the activation is successful you will get a success message and you can click Finish.