As a supplier/manufacturer, do I have to have a license?

If you are just furnishing material or equipment, you are considered a manufacturer or supplier, and no license is required.  Under normal circumstances, a supplier can ship the product to a jobsite with no further involvement on the project.  However, if you bid to furnish and install, even if you plan to hire a licensed contractor to do the installation for you, your firm is required to hold a license.