In all States excluding Maryland you need to have a Sellers permit in order to legally operate a vending machine business.
Maryland is the only state that doesn't require a sellers permit for vending machines.
You may however have to pay sales tax on the products you vend from your machine so you may also need a sales tax sticker to place on your vending machines and add the sales tax into the cost of the vended product which you will then pass the sales tax onto the state.
Getting a sales tax permit for your vending machine doesn't cost that much and is easy to obtain just check with your courthouse or city about getting the sales tax permit as well as the vending machine license.