hehe i knew this would be a bit confusing.
thanks for the post i'm sure you are speaking for a lot of people who have same question.
in process tamer, you must open the configuration dialog (double click on tray icon or right click and select configure)
from that dialog you can hit the about button and enter the code.
in the next update of process tamer i will make it launch the configuration gui about box.
let me explain why it is the way it is:
people want process tamer to be super fast and efficient. for this reason i decided not to put any license checking code in the little 150k process tamer tray tool, and only put it in the separate configuration tool which is only loaded on demand.