Licensing is the legal permission to use a photo over a set amount of time. In real estate photography, this contract is set between the photographer and the real estate agent, and it gives the agent the right to use the photographs in their listing. This is a non-transferable license, meaning the agent cannot sell the photographs to a third party. Typically, the license will be active until the home has been sold, and all rights of the photograph go back to the photographer.
Not all states have the same licensing requirements, and as such it is vital that you as a photographer research the requirements within your own state. As for pricing a license, this is also a unique variable with no set price. For example, there may never be the same deal for turnaround time, market real estate pricing, competition pricing, the area of use, usage rights, just to name a few. It will be at the discretion of the photographer to create a pricing guide for their license. For example, drone photography often requires licensing to safely photography in accordingly with the FAA, and some commercial photography requires permission and permits by the city and state.