NR rated movies

Does anyone know the age requirements to watch an NR movie in theaters? I’m going to see terrifier 3 with a couple of friends tomorrow who are all 17, but I’m a bit younger than them so I wasn’t sure if they’d let me in. I’m planning to just order tickets online because I was able to watch Halloween kills in theaters when I was much younger, although that one was rated R not NR so I’m not fully sure. If anyone has any answers please let me know!