There are three types of installers for GT (GenomeTraveler), for Mac, Windows, and Linux.
If you are going to try GT, download the installer from here, install it, start it and a trial license request window will open and you can get a trial license.
If a license is purchased, the DVD containing these installers will be delivered.
Also, if there is Version Up while using GT regular version, check if the latest version is released, and if it is released you can download the latest version with one click.