Some dealers may "card" you before you pick up a toy, but that's a policy of the individual dealer, not the show. (MisterHappyJr was not permitted to pick up a shotgun at a local dealer...and he helps me teach Trap!) If you're a new shooter, it's a cool experience. There's a lot of stuff to see: new, old, weird.... I've been around these things for a long time, and I always see a new - to - me item, or learn something new.
I'd just not say, "Excuse me, I'm not licensed, so I can't buy anything....can I get my greasy fingers all over your expensive equipment?" Instead, if you see something you are interested in, say, "May I see that one?" If they card you, say it's not in yet....you've lost nothing.
BTW - The Jerky guy does not require ID!
You can also join GOAL there - that's a good investment, too.