That’s a great question, Marie!

From what I’ve been told, caffeine doesn’t completely lodge into the receptor and remains there unshakable. Instead, the binding is temporary. After a few seconds, the caffeine molecule might be knocked out of the receptor and then shortly afterwards the same or another caffeine molecule might plug the receptor again. So thinking of caffeine as permanently plugging the receptor is a bit of a simplification.

Either way, enzymes in your body eventually break down the caffeine. According to this paper, “the mean half-life of caffeine in … healthy individuals is about 5 hours.”