What is the name of your state? Ohio
If a person has a retail vendor's license, are they automatically, legally ok to sell a patented product without permission from the inventor/company who sells/makes the product?
What is a "retail vendors license?" If that is a state or local license, then it has nothing to do with the sale of patented products.
If the license is obtained from the inventor or company who makes the product, then you would need to look to the language of the license.
But more to the point -- there is a "first sale" or "exhaustion" doctrine in patent law, which states that once the patent holder sells a device that is covered under his or her patent(s), the patent holder can no longer assert rights over that particular device. In other words, if an inventor sells you a patented widget, you can do pretty much whatever you want to do with THAT particular widget -- resell it, rent it, detroy it, whatever. You can not reproduce it, of course, without permission -- but that particular widget is yours.
What exactly is the situation you find yourself in?
