Do I HAVE To Consume Protein Immediately Post-Workout?

If you fail to have protein immediately after your workout, you may as well kiss your gains goodbye. That is what I was told when I started lifting, and what I have been preaching to my clients over the past few years when it comes to the anabolic window and protein intake. Is this still the case, or has current research changed the way we might perceive protein timing? I answer this question from a scientific perspective.