I live in Philadelphia. My lease has been up for 6 months and we want to move out. My landlord is trying to tell us that we have to stay here another 6 months because the lease automatically goes to another year! I thought it was month to month after the lease was up. Also he knew someone moved out and my finacee moved in and did not make another lease. Am I obligated to stay here?

The lease automatically renews for another 6 months only if it says so in the lease. If it doesn't say so in the lease then it becomes a month-to-month lease. Read your lease carefully.