Background verification for roommates rental

[Albert George]

I have a place that rent out to room mates. The question I have is there a no cost or low cost options to verify identity/background  of people I rent out. 

What information i should collect from them. Is it  enough to get a copy of the license alone. I don't collect any background verification fee.

Should I do leases for these room mates or verbal lease which means it is a month to month.