I'm doing better, but I now have a problem

I've been trying to avoid eating after 7ish, but our study halls start at 7:45 till 9:45 at night. So I can generally finish all my hw and be okay, but then we almost always have snacks in the dorm at late check in (10pm). Sometimes we'll have cookies, or brownies, or crackers, or nachos or some other yummy snack that the duty person brings... And oh my god, we had the MOST AMAZING snack 2 nights ago... it was the best mac and cheese I've had in AGES.
Okay, so any ideas on how to avoid these treats? I could just check in and leave, but then I miss out on all the great food

Maybe I should get in the habit of taking some of the snack, bagging it up, and eating it later on?
-- Oh, and I really like the jar thing.. it's silly, but sometimes I'll be like... "Well, I could eat this cookie, but then I wouldn't be able to add another dollar tomorrow!" Yeah.. it's weird, but it helps.