Almost all of us have forgotten to remove the plug at one time or another. A good way to help you remember it is to put it somewhere that you are guaranteed to see it, thereby helping you to remember to put it in.
1) get a small chain like is used for the pull cords on ceiling fans, use it to attach the plug to the steering wheel of your boat. Makes it hard to get in & back the boat off the trailer & NOT see the plug.
2)attach it to the hook on the winch on the trailer. You'll see the plug when you unhook the winch strap.
3)attach it to one of the hold down straps or the motor toter on the back of the boat.