There are two versions of the Gearbox software, one is the version that ships with Line6 devices like the Toneport I own and is targeted at Line6 devices, this is a stand alone app that will provide processed output to your recording software or direct to your monitors, the other is a VST plug-in intended for using within DAW hosts like Cubase, Reaper etc.

The stand alone version comes with the devices, the VST version is a purchasable extra, it sounds like that is what is for sale. But I'm not sure it will work without a Line6 hardware device, though I could be wrong.