I hate it when I have to pretend I havent seen something

At work one of the new girls keeps breaking the rules , I dont mean drugs but she lets guys do licence what they want to her , I personally dont care what she does but I just dont want the club to loose their licence because I really like were I work and I need to keep my job , I know she does it because ive seen her in the dance room as we had an group dance. I have nothing at all against her , I was going to talk to her about it but I dont want an massive fall out. I also dont want to get her into trouble as we get along and she hasnt done anything to me. I feel like if she carrys on she will get fired but I dont want to be the reason why she gets fired. I also feel like I have to tell someone , its so hard for me because I dont want her to get into trouble but I was in that dance room whilst she did those things all the way through.