곤

Used to, would (habitually)

Marks something that happened repeatedly over a stretch of the past, and it almost always comes with 하다 behind it: we used to have dim sum every Sunday, she used to quiz me every night, I make snacks for everyone, editors sometimes throw in their own comments. It needs the repetition — for a one-off past event you would just use the plain past. Note the lookalike 그러곤 in one line, which is a different thing meaning 'and then'.