My daughter rents a house and has lived there for four years with her boyfriend, he is not on the lease.
After my daughter got laid off two years ago he was paying the rent. She returned to work and now they are breaking up, he told her to get out, with just a day notice.
It seems that because he isn't on the lease he shouldn't be able to do that.

Thanks for any info.

No he can't kick her out when he is not on her lease. He can go to the landlord and request that she be evicted but if the rent is paid and there are no problems then I don't see the landlord even doing that.
If he did manage to get her evicted I think he would be running the risk of him being evicted as well. Why doesn't he just move and leave her alone?

If he is living there without being on the lease, even if he's been paying all of the rent, his rights are not superior to hers. At best he has an implied month-to-month lease from her. She could evict him, not the other way around.

But, anytime you are dealing with a relationship falling apart, the personal aspects can be more important than the legal ones. For example, is she in any danger of being physically hurt if he gets angry? Even if not, it can get pretty messy if she evicts him and he choses to stay, so they are both living there until she can enforce the eviction.

My gut says she should tell him to get out -- but, ensure that she (and her property) is protected (friends, police, etc) in the event it gets violent.

First, whether he's on the lease or not, he can't kick her out on one day's notice.

Second, if he's not on the lease and she is, he can't kick her out at all. The house rental is in her name and he lives there on her permission. Since she's on the lease and he isn't, he is her tenant on a month to month basis. If she wants him out, she can give him 30 days notice to vacate. If he doesn't leave, she files for an eviction order.

If he tries to force her out, she needs to call the police. She shows the police that the lease is in her name and they will deal with it.