Turn this on for daily or recurring monitoring of the same destination search or hotel/search URLs. The first run returns all matching hotels as NEW. Later runs normally return only NEW, UPDATED, and REAPPEARED hotels. Turn on "Emit unchanged" or "Emit expired" only when you also want those hotels returned (and billed). State is kept separately for each mode/destination/URL/filter setup; use State key when you want to name or deliberately share a monitoring campaign. To continue one specific interrupted run instead, use Resume from a previous run above.