If you have a lease-option contract, you can choose to move out when your lease ends. At this point, you’ll most likely need to walk away from your option money and any credit towards the house you earned with your rent payments. But if you have a lease-purchase contract, you’re contractually obligated to pay the seller in full (this can be in cash or with a loan from your mortgage lender). If you can’t make the necessary payment, it’s best to contact a lawyer at this point to discuss your options.