When you add an endorsement to your insurance policy, it stays valid as long as the policy does, or until it is removed from the policy. If there is a time limit for the endorsement, it should be listed in your policy details. An endorsement can often be renewed with your policy, as long as certain requirements are met. For instance, a new car replacement endorsement may only apply while your car is a certain age or has a particular mileage limit, which means it will be removed once the age or mileage has reached its limit.