Gravitorium is shareware. You can try out Gravitorium free of charge for a period of 21 days, but after that we ask you to pay a small fee for its use in order to fund further improvements to the software.
Visit this page to register: http://www.rightword.com.au/products/gravitorium/register.html
You will be asked to provide us with your preferred registration name and email address and we will send you back a registration key via email within two days.