I assume it just wipes when it ends, but the logging out makes sense as well. There were times when events have ended in the past, but as long as you stayed logged in to not clear the event as closed, you could still find event res from explorers. this was way early in the game though, but i can see mechanics of this buff being this way too, but dont have the patience to care to test, considering this game needs refreshes to stay working, if its not busted af crashing or even operational with all the issues it has had.
I thought for sure i had the pre-sending of explorers explained too but that has been messed up for 5 years now.