When you have your User Name and License Key follow the steps bellow.
1 - Click on the red smiley face at the right bottom of the screen, select "Codec properties" :
If you don't see the red smiley face try to go to Start / All Programs / Morgan M-JPEG codec V3 / Quick config
2 - Click on [About] :
3 - Click on [Register...]
4 - Enter your User Name and License Key by respecting the case :
5 - 'Registered' appear under the logo (32-bit) or 'Demo' disapear (64-bit) :