First of all, you should know the state and its concerned department that issued the business license you are looking for to verify. Usually, people get business licenses from the state they are reside in.
If the business activity crosses the state line then you can track the business license by contacting the concerned departments of those states where the business is being operated.
Make sure you have contacted the right authorities or the department that issues business license for the state. Generally the Division of Corporations and Department of Professional Regulation are the concerned departments for verifying the business license.
Visit the website of the concerned department and enter the name of person who got the business license in the required areas on the website. It will provide you details about the business license issued on his or her name.
If you fail to find the information with the name of the person, then you should verify it by inserting the license type into the required fields on the website.
You can also verify a business license quite easily if you have got the license number, if you have got it. Just insert it into the required field and you will get the details about the business license without any problem.