Is it to evict a paying tenant after buying a duplex in Maine?

[Kathy Welch]

I am purchasing a duplex for myself to live in one unit and my adult daughter to live in the other unit.  The unit I will be in will be vacant per the contact I am currently under.  The other one has a lease that expires Jan 1, 2018.  When can I notify the tenant they have to leave and am I able to just tell them they have to leave so I can have someone else in that unit?  I am in Maine.