it is in the main Quest tab and its the only thing i have to still complete.
That's strange, as according to the game file, the conditions for this event are following:
def Laura_chapter_one_season_three_secret_studying_setup():
...
conditions = [
"not EventScheduler.check('Laura_chapter_one_season_three_secret_studying')",
"chapter == 1 and season == 3",
"Laura.location not in ['hold', Player.location, Player.destination]",
"Rogue.location not in ['hold', Player.location, Player.destination]",
"Laura.home not in [Player.location, Player.destination]",
"'bg_girls_hallway' not in [Player.location, Player.destination]",
"not Party",
"time_index not in Laura.schedule.keys()",
"time_index not in Rogue.schedule.keys()",
"renpy.random.random() > 0.75 or season_completed",
"Laura.is_in_normal_mood()"]
...
So there should be a ~24% chance to make this event appear OR the current season is supposedly completed; the latter should rather be the case if all other objectives are completed in this season.
Laura must be also in normal mood, what could be easily missed.
Making Laura or Rogue or anyone else following the player, as suggested before, is not allowed either as "not Party" defined
Laura and also Rogue may not be in any current player's location either.
No idea about these time-index conditions if something could still be ticking there.
As I suggested before: upload your save game for others to check out if you are still stuck there, or rather don't want to play on without completing any optional objective.