Lesson learned the hard way, right? A tiny tube of grease costs nothing compared to a new crank or bottom bracket. Once it's seized, you're looking at soaking it in penetrating oil for days, maybe even using a heat gun carefully. Got a decent crank puller ready for the fight?
Actually, Robert, you really don't want to use heat on an aluminum crank arm. It can wreck the temper of the metal. A big dose of patience and penetrating oil is the safer bet.