expiration_date

Expiration_date solves the time-bound listing problem cleanly. Limited-time merchandise (event tie-ins, seasonal collections, regulated expiry food) gets an explicit expiry; channels auto-remove items at the specified date without manual intervention. The pattern is most useful for catalogs with significant time-bound inventory — event merchandise, holiday seasonal, regulated-shelf-life food and beauty products.

Google's 30-day cap on expiration_date is worth noting. Beyond 30 days from the last feed fetch, items get auto-flagged for re-evaluation regardless of the expiration date set. The practical implication: for true long-tail evergreen products, just leave expiration_date empty and let the default 30-day refresh cycle handle item presence. Use the field specifically for items where you want explicit expiry shorter than the default.

The strategic use case: combining expiration_date with limited-time campaigns. Pop-up products, collaboration releases, anniversary editions all benefit from explicit expiry to avoid the catalog drift problem where time-bound items linger past their relevance.