This stuff lasts a very long time
I have a Nolan helmet that was coated over a year ago that still beads up very well if not just as good as the day I applied it
My Arai XD shield is pretty scratched up from riding offroad. After applying Raincoat a lot of the smaller scratches go away and the shield is much easier to see through.
I ride year round and often at night in the rain. Raincoat allows me to see clearer and ride much safer. It's amazing stuff