Warranty
Warranty is a term some panels use for a refill period attached to a service, and it commits the panel only to the window, trigger and scope written in the service terms.
In catalogues the word often appears as a tag in the service name, sometimes followed by a number of days. It does the job that refill does in other catalogues, and the mechanics behind it are the ones set out in the refill entry. Panels often use warranty, refill and guarantee for the same thing, and often is not always: one catalogue can sell refill and guarantee as separate tags on the same service, so the written terms decide and the word does not. The name alone does not tell you when the period starts: from the order date, from delivery starting, or from completion. On a slow order, that difference can use up much of a short window before the last of the delivery arrives.
Read what the warranty covers. Some cover only falls below the start count plus the quantity ordered; some exclude orders that finished as partial; some are void if the link changed, the account went private or the username was changed during the period. Some require you to request refill yourself, and some limit how often you can request it, so a drop that continues after one refill may not be covered twice.
A number in the tag is not the policy. A service tagged thirty days and a service tagged lifetime can rest on the same paragraph of the same terms, and that paragraph is what a claim is read against. Where the terms say nothing about refill at all, the tag is a sales label with nothing behind it, however many days it names.
The weight the word borrows
On a panel the word carries none of the weight it carries on an appliance: no refund, and no commitment that the engagement will last. It does not return money when the count falls, and it does not extend beyond its written period. The word sounds like a product warranty, but on a panel it names a refill policy, so read that policy rather than the word.