When you seek the help of a real estate agent or broker to find a buyer for your property, the listing agreement you sign serves as a contract that stipulates the time period during which you give the broker exclusive right to market your property and attract a buyer. It also specifies the commission arrangement you accept. Most listing agreements include an extension, or broker protection, clause that outlines the conditions and number of days under which the broker's entitlement to a commission is guaranteed after the listing agreement expires.
Your listing agreement gives the agent a specific number of days after it expires to provide the names of potential buyers contacted. If you sell the property to someone on this list during the protected time frame, the broker protection clause requires you to pay commission to the agent as if the agreement was still active. This defends the agent against buyers who try to save money by dealing directly with sellers. However, if you relist your property with a new agent who sells your property to a prospect from the first listing, your commission obligation lies with the selling agent only.