Like most contracts, the seller has the right to request a shorter or longer time period if both parties agree. Many include a renewal clause, which provides an option to extend the listing period if both parties agree.Often brokers present sellers with a standard listing agreement (an agreement which contains "standard language"). Generally, automatically renewed contracts are enforceable everywhere. A quick overview of the Massachusetts Association of Realtors exclusive right to sell listing agreement. Most minor changes can be made right on the contract, but bigger changes might need to be added to an addendum at the end of the agreement. Many states do not have a clause that allows the client to cancel the listing agreement unilaterally.