In warmer climates it is a perennial, colder climate it's an annual. It is in the verbena family, they are salt tollerent, invasive and toxic to children & pets if unripe berries are eaten is fatal. If you decide to pull out what is coming into your yard use long clothes gloves because you can get a rash from the leaves so bag & trash those leaves. I wonder if you neighbor has children & pets and maybe their are unaware of it's danger.