Ways to boost protein in my situation?

My seasonal work arrangements have me in employee dorms with a small cafeteria and limited vegetarian options.

The larger problem being limited hours. I usually like to eat a bit later in the evening after my shift. I’ve try to take some stuff back when I can. I don’t have a microwave or fridge . Ive been trying to supplement with nuts, peanut butter sandwiches, and protein bars. I’m considering adding in protein shakes/powder that don’t need to be refrigerated as well.

Any tips? Thanks!

*I originally posted this in r/vegetarian and it was removed which I understand. I have no clue where to ask this. Also, if you couldn’t tell by my situation, cheap would be good.

Ways to boost protein in my situation?