Matt,
Once it is downloaded and registered you never need to be online again. We have frequent automatic updates that you can only get when connected to the internet, in which we encourage our users to get when they can.
The information you enter into the program stays on that computer, unless you use the synchrocize button under "Help" which will place all your deer and their score to your account online. Regardless, we never see that information. We will be creating a huge database that is voluntary to map out buck size, movement, and other things in the near future, but it is not available yet.