Suspected drug use at rental house

[Jodie Newby]

I live in North Carolina and we have a rental house in which we suspect there is drug use going on. I was there yesterday to check on the the plumbing because there was a problem. When I went into the kitchen to check the faucets there were 4 glass pipes on the counter that looked like marijuana pipes. There is a mother & her adult son living there, he is a glass blower. I know if I say something they will say the pipes are for tobacco use but he seemed high yesterday and she didn't want me inside the house, especially in the kitchen. My question is can I legally enter the premises and look around since drug use is suspected? Their rent is paid so the rent is not the problem.