Before you lean on any warranty or service contract, find the part of the paper that asks something of you. Most of them have one. They describe what the seller will do, then add a list of what you must do for that promise to stay in effect. That list is the maintenance condition, and it is easy to miss because it reads like housekeeping.
What a maintenance condition usually asks
Read for the verbs. Look for words like must, shall, required, keep, schedule, and provide. Typical asks are routine service by a qualified person, keeping a record of each visit, using replacement parts of a stated type, keeping the equipment in its installed location and configuration, and reporting a problem within a stated window. Each of these can be broken without your noticing.
Check the wording of the service itself
Find the exact service the paper names. Some require a full inspection. Others require a filter change or the cleaning of one particular part. Some name a qualified technician, some name a licensed contractor, and some say only 'professional'. Write down the exact phrase. Then ask the seller in writing what the phrase means, who qualifies, and whether a homeowner doing the task counts.
Find out what counts as proof
A condition is only as useful as the record that shows you met it. Ask what the paper accepts as proof: an invoice that shows the visit, a service tag, a signed log, or a photograph of a label. Ask whether the record must come from the person who did the work. Keep copies in the same folder as the signed contract, and keep the original invoices, not only a summary of them.
Know what a missed visit can do
Read the paragraph that follows the condition. Many papers say what happens when a condition is not met, such as a denial of a claim tied to the missed care, or a reduction in what is paid. Some papers say nothing and leave the question to the claims staff. Ask the seller directly how a late or skipped visit is handled, and get the answer in writing before the visit window closes.
Match the condition to your own calendar
Compare the paper's required interval with the service guidance in the equipment's own material and with the seasonal walk-throughs on this site. If the paper asks for a visit the equipment does not seem to need, ask why. If the equipment needs care the paper never mentions, ask whether that care still counts. Write the questions down and keep the answers with the contract.
Keep the list short and current
Make a short list from the paper: each condition, its exact wording, the proof it requires, and who in the house owns it. Mark each one as you complete it. When the equipment changes hands or the paper is renewed, read the list again, because the conditions may have changed.
For the published figures on service life, see the tables on this site, which show planning guidance for each system without tying it to any contract. The paper you signed is still the only place that states the terms that apply to you.