Consequences
The back of each major arcanum also lists its potential consequences. You mark a consequence when a move tells you to, or when you roll a 6- on a move and the GM tells you to mark one.
You get to pick which consequence you mark. Whatever that consequence says, it happens. Don't mark a "nested" or indented consequence unless you've already marked the consequence under which it is nested; beyond that restriction, you can mark them in any order. You'll probably want to start with the ones near the top, though.
Consequences can be marked only once (or in a few cases, once per check box). There's no standard way to uncheck a consequence; they're a limited resource. Each time you mark a consequence, you must mark an empty check box.
What happens if you mark all the consequences? That depends on the arcanum. Some include a consequence that has the object break or vanish, which makes the question moot. Others require you to mark a consequence in order to use one or more moves; and if you can't mark a consequence, you can't use such a move. But if an arcanum says to mark a consequence as a result of one of its moves, and you've already marked them all, then you and your group have to decide what happens. Maybe the item is safer to use now, since you can't suffer any more consequences. Or maybe the GM gets to make something up, on par with the consequences that we've already seen in play. Decide together, case by case.