I'm a general contractor. A subcontractor agreed to install driveway pavers, that I supplied, for a set price, that was about the same as other bids. He sent me an invoice for almost twice what was agreed to. Now he threatens to file a lien. I don't think he can, based on what I understand about AZ lien laws, especially since I paid him with a check marked "in full of account", which he cashed, for slightly more than the agreed-on amount.