if he challenges it, yes.
You are required to provide at least 7 days notice before the end of the rental period for a month to month tenancy in your state. An tenancy at will such as you have will be treated as a month to month tenancy. I do not know if NC goes by calender months or 30/31 day months so trying to determine what the first day of his month is problematic. I would treat it as calender months. It is always a safe bet.
So, since it is already too late to get him out before the end of May, give him a written notice terminating his tenancy as of May 31. Hand him a copy. Hang one on his bedroom door. Post one on the front door of the house.
Then, if he does not leave at the end of May, you will have to file an unlawful detainer suit and ask the courts to evict him.

