I would think it would depend on your state. Ask your DOI or post what state your in so someone from your state can share what they know. In Tennessee the agency doesn't have to be licensed. Just the Agents.
It does exist and many states require an agency license if you want the agency to get paid instead of you personally. In most states, the entity that is receiving the commission must be licensed to do so. However, the agency license is based off of the LOA (Lines of Authority) of the principal (you.) So, in most states (except a few) all you have to do is pay the licensing fee for the agency license, and tie the license to your agency EIN. You'll have to submit to the standard check, but if you got your individual license, then getting your agency license should not be a big deal.
In some states, such as Texas and Utah, you must have an agency license if you wish to recruit agents under you who have a DBA license, or if you wish to have your agency receive an assignment of commission. If you have a non-res license in either of those states, you "technically" (since it is rarely enforced) need an agency license PERIOD if you wish to have anyone under you. Companies are suppose to check and make sure you have an agency license before allowing you to recruit and appoint subagents. That being said, it is one of those rarely enforced rule and the only reason I found out is that one of my carriers actually enforced the stupid rule so I had to go get one.