Hey Troopers!

Got a Noob question for you (since I'm only a month-ish into the game).
Souls and soul fragments from events: Do these expire/disappear after the event is over? I have a ridiculous amount of Striker souls and fragments, and since the event ends in about 6 hours, I don't want to lose out on them. (I wish this damn sac event would get here already!)
Thanks!!
\m/