A trip's itinerary is removed from the Trips List approximately 24 hours after all trip items in the itinerary are complete. After a trip's itinerary is removed from the app, you can still view it on Expedia's website by signing in to your account and clicking Trips.
Expedia differentiates trip itineraries by their itinerary numbers. Trip items that are booked in separate transactions are assigned different itinerary numbers. When trip items are booked separately in this way, the trip items could be removed from the app's Trips List at different times.