What’s the age limit for buying tickets, my niece is 18 months does she need a ticket?

Questions through Google are manned only by volunteers who happened to go to the same place of business. For venue specific info you have to call them. Lastly, are you sure you should be taking an infant to someplace that gets really loud, sells beer, and can be flooded by unruly fans? Kids yeah, but infant? No. Leave the kid at home so you don't endanger their hearing. "Because your baby cannot tell you how loud is too loud, use a general rule of thumb, that noises less than 80 decibels should not cause hearing damage, according to The Children’s Hearing Institute. This is the equivalent to noise in a restaurant or in city street traffic. A normal conversation is about 60 decibels."

You would have to call the box office on that question