Unfortunately, it's impossible to buy, download, or renew the license for this application because the official website is out of business. I have checked its old domain and it now displays a DNS error. You might need to use another application for your needs.
Luckily, there are other applications available for Mac that have the same functionality. For example, you can use MacFamilyTree to install on your Mac: http://www.syniumsoftware.com/macfamilytree