Use it at your own risk, it may be disabled if you use it out of the ip range, if your lucky it wont..
. Go to
http://www.whmcs.com/hostgator/2. Enter "216.172.164.64" in the domain field (without the quotes of course)
3. Click on button "Check eligibility"
4. Click "Sign up"
5. Click "Update cart". After that you will be redirecteed to registration form.
6. Fill in your information and be sure to fill in a valid email because you will get your key there!
7. Finish your order and within few minutes you will receive totaly free WHMCS key!
Enjoy!