Buying my first rental with existing tenants

[Michael Karl]

I am currently in the process of buying a 3 unit rental in the Buffalo New York area.  All three units are currently rented.  One unit the tenant has only been there for 3 months and is currently under a 1 year lease.  But the other 2 units the tenants have been there over a year and are now on a month to month term.  After the purchase can I have the month to month tenants sign a 1 year lease?