Here's the rule for canoes in PA.... If you are going to use a Fish Commission Launch (to launch or recover), the canoe must be Registered, or you may buy a Launch Permit to launch. If you are going to put a motor (gas or electric) on the canoe, it must be Registered.
I live in the Southwest corner of Pa, and used to float the Yough from Layton to Coulter. We would launch where the river was next to the road, and take out at a private ramp. The canoe did not need to be registered.
If you are going to use it in a State Park, I'd check the regulations at the Park office. That is where you would buy a launch permit, but there may be a park rule prohibiting the launch of any boat except at the approved fish commission launch, requiring the permit.
Canoes are a lot of fun. You won't regret buying one.
Make sure you check out the laws for boating at the fish commission site: http://www.fish.state.pa.us/mpag1.htm