If you've just installed KD Max and you're greeted with an error message saying Key Not Found - don't panic, try the below solutions.
Ensure that the white licence USB is firmly connected to a USB port as pictured below.
1. Try another USB port for the license key lock (the white/grey one, which has CAB.... Written on it)
2. Restart your computer.
Or
3. Right-click on the KD Max icon and run the program as an administrator