Are you required to buy Barnes & nobles?

I have never really hang out there, but i just moved to a small town and I'm thinking about frequenting the store to catch up on some reading. I'm i required to buy a book every time i go or it works as a regular library where you can just go and read. and how about the Starbucks store can i just walking with a book in my hand and order , seat and read?? i don't want to look like a retard ...