For commercial advertisers, it does not go back at all. The Meta Ad Library is a live view of what is running right now, not an archive. When a non-political ad stops, it leaves the library and there is no way to retrieve it.
This catches people out constantly, because the word "library" implies a back catalogue. Only political and social-issue advertising is genuinely archived, and that archive runs seven years.
What that means in practice
You cannot answer questions like "what were they running last Christmas?", "what did they test before this campaign?", or "how has their messaging changed over two years?" from the library itself. That history was never published for commercial brands, and it is gone.
What you can see is every live ad, its full copy, its placements, its destination URL, and the date each one started running. That start date is the important field, because it is the only public performance signal an advertiser cannot fake. An ad still running after three months has survived every optimisation decision that brand has made in that window. We wrote up how to read it in how to tell if a competitor's ad is working.
The practical consequence
Anything you want to keep, you have to capture while it is live. A competitor's best-performing ad of the year is retrievable today and unretrievable the week after they pause it.
This is the real reason ad intelligence tools exist. The libraries are free and complete for live ads, so what you pay for is history the platforms discard, plus monitoring that catches a competitor's next move rather than their last one. If you are researching one brand once, the free route is genuinely fine.
The other thing the library never had
While you are recalibrating expectations: it does not publish spend or impressions for commercial advertisers either. We checked 2,108 live ad records and exactly zero carried a spend value. Those fields exist, but Meta marks them available only for political and issue ads.