A service contract is sold with a term, and the term is only one of the limits on it. Many papers also end coverage at a set mileage, at a set age of the item, or after a set number of operating hours, whichever comes first. Before you compare plans, decide how long you expect to keep the vehicle or appliance. That answer tells you which term is worth paying for and which one pays for years you will never use.
Write down your own horizon
Write one sentence stating how long you expect to keep this item, and what would make you sell or replace it sooner. A household that plans to move, change cars, or rebuild a kitchen should write that down, because a long term on an item you are about to leave behind carries the cost of years you will not spend with it. Note whether the plan ends after a set span of time, at a mileage, or at an age. Each one ends differently when the item is used harder than you expected.
Check which limit ends the coverage
Ask the seller which of the limits ends the coverage sooner. A plan that runs a long time but stops at a low mileage may end before the item is worn out, and a plan with a short time but a high mileage limit may end long before the item is worn out. Ask whether the paper counts miles from the item's own odometer or from a reading taken at sale, whether the paper accepts a reading supplied by the owner, and what proof the owner must keep. The paper should answer these in plain terms. If it does not, ask for the answer in writing.
Compare what happens at the end
Find the clause that describes what happens when the term or the limit is reached. Some papers simply stop. Others state whether any part of the price paid is returned, and by what method. Do not assume either. Read the end-of-term clause together with the cancellation clause, since the two often use different wording. This guide publishes no figures. For the rules that govern the contract, use the state page on this site for the state the paper names, and check the paper against it.