This can happen following a major Windows update.
The WebEasy serial number is actually still valid.
Solution:
Please uninstall the program, and then delete the program folders
C:\Program Files (x86)\Avanquest\Web Easy Professional 10
and/or C:\Program Files (x86)\Avanquest Software\Web Easy Professional 10 if present.
Restart Windows.
The new install will not disturb your existing projects. They are stored apart from the program, in your Documents\Web Easy\ path.
Please download WebEasy 10.2.3 from the following page:
http://downloads.vcom.com/support/WE10.2.3.407-Pro-ENU.exe
Click the Download button and save the file.
Then run the file WE10.2.3.407-Pro-ENU.exe to install WebEasy 10. However, when it finishes installation do not run WebEasy yet.
Go to the program folder C:\Program Files (x86)\Avanquest Software\Web Easy Professional 10
Right click on Webeasy.exe and go to Properties.
Go to the Compatibility tab and verify that compatibility mode is NOT enabled.
Make sure that "run as administrator" is also not checked.
Click OK.
If you have BitDefender, or Trend Micro software, you will need to create an exception for WebEasy to allow it to run.
In BitDefender:
Click on the Settings icon on the top right of the program.
On the list of items on the left, select Antivirus.
Click on the Exclusions tab at the top.
Click on the Excluded Processes link/button.
Click the Add button.
Click Browse and locate the WebEasy executable file and select it. This is located in C:\Program Files (x86)\Avanquest Software\Web Easy Professional 10\webeasy.exe
Then try to run the program.