License, simply stated, is a document issued by a competent authority giving the holder permission to perform certain acts, use or own a product. For instance, to own driving school and impart training to prospective drivers of light or heavy motor vehicles, you need a license from the department of transport of the state where your school is to be set up. This is not to be confused with driving license that a person must possess to drive vehicles on public roads. However the possessor of the driving license is not authorized to drive vehicles when in a drunken state. You cannot drive when you have consumed alcohol regardless of the fact whether you are in an inebriated state or not. So no drunk driving.
Apart from driving school , even to own a business, you need to be licensed by the local body/municipal authorities. This issued licence for business purpose is called business license. In this internet age, you even need a software license that will permit you to lawfully use software or else it may be construed as an offence and violation of cyber laws. If you hold a software license you are authorized to use or distribute copyright protected software.
If you own a product under a license, a serial number is affixed to the product to identify your ownership and in certain cases the number can also be alphanumeric in nature. There are other licenses as well like ontario drivers licence which are used on licence plates.