There’s always some risk in accepting long-term guests into your home. Even if it’s your best friend, a family member, or someone who truly needs the help, it’s a big responsibility for you to house someone, and it’s an even bigger responsibility for the other person to be a good houseguest. With no lease legally binding them to pay rent and bills, there’s very little you can do if their stay turns into a terrible situation. Nobody wants to feel like a burden to their host, so it’s imperative to get out promptly (unless you’ve otherwise specified that both parties intend for this to be a long-term arrangement) and treat the home that they’re staying in with respect and to live under the rules of their hosts. You would think this would be pretty easy to do if someone allowed you to live rent-free in their home, but you’d be surprised.