Others may have already done this but if not...
LeaderTask can be made portable (worked for me anyway). Oh and you can still do this even if you already installed it.
Copy the LeaderTask folder (in the Alzema folder in Program Files) to your USB key.
Start the application by clicking on LeaderTask.exe in the LeaderTask folder.
Once the programme has started go to Help -> About and enter the registration info provided by Giveaway Of The Day in the readme.txt file into the registration dialogue box.
Restart application it is now registered.
Try it on a different computer - still registered (application retains registration info in it's own folder).
Others seem to have said that the application quits on them and I have noticed the same behaviour running from USB key but it seems sporatic.
Enjoy!