All home improvement contractors in New York City need to be licensed to perform the following services, among others:
construction, repair, remodeling, or addition to any land or building used as a residence. This includes, but is not limited to, the construction, replacement, or improvement of basements, driveways, fences, garages, landscaping, patios, porches, sidewalks, swimming pools, terraces, and other improvements to structures or upon land that is next to a home or apartment building.
In New York City, there is also a license requirement called a Home Improvement Salesperson License for those who "solicit, negotiate, or offer to negotiate a home improvement contract with a property owner".
Click here to verify licensing in New York City.
Remember, if your contractor is unlicensed, they cannot enforce your home improvement contract against you & they are subject to arrest & prosecution.