The shop will allow you to buy items to customize your desk! Customizing your desk might change how the nights go.
I should probably inform you that my gallery appears to be bugged, I have yet to get anything to unlock through it. I think it has something to do with the fact that data from the demo seems to have carried over into the main game, I played 3 nights of the demo and when I booted up the main game it started me at 3, I am now at 9.