It also shows that the company has the required training and experience to obtain the licensing, which means your job will be done to the code requirements.
This protects you the homeowner if something is to happen to your home or one of the contractor's employees is hurt while installing you air conditioning system.
Also, ask a few questions about the companies hiring and screening process of their employees.
Don’t forget to ask the contractor for referrals of customers where they have done a similar air conditioning job.
Ask the testimonial a few questions to get a feel for the contractor that will be installing your air conditioning system and what you can expect from the contractor.
I would recommend going and looking at the quality of workmanship if possible.