The Videopad download page offers the latest. Randomly, it may be the 32- or 64-bit version. The link you downloaded is the current 64, and after being registered it won't expire.
For one-time licensed users upgrades are free for up to six months from purchase date. After that, VP will continue to fully function but a fee is required in order to register the newest. Retain your old install file and registration info. If there's an issue, you can always revert.
There's never a mandate to update, and it's often best to stick with what's working for you. But you can always test drive the latest, even after the six-month grace period expires, to see what has changed.