Why do I get "Invalid license key, please input a valid key" error?

he reasons might be:
1. You entered a wrong license code. We highly recommended to Copy & Paste the license code instead of entering it directly. Please make sure there is no blank space before and after the license code.
2. You used a license code for another program to register the program you want. Please make sure you use the right license code to register the correct program.
Or, please contact our support for help.