Keen stratagem disappears

In PVE modes, some battles have multiple encounters (sometimes called waves or phases in some modes). It's what tracked by the "1 / 4" at the top of screen. 

Kleya's ability "This Is Do Or Die" only grants Keen Stratagem "until the end of the encounter," so it expires after each wave/encounter. In contrast, Captain Drogan's ability "Battle Plan" grants it "until the end of the battle," so it would persist between waves/encounters. (Note that Cassian's "Varian Skye" grants an ally VIP "until they are damaged twice," so if they aren't damaged twice, the VIP also persists.)