Hi. I’m still a newbie trying to get my ducks in a row, administratively, so I’m just here to chime in with my two cents.
I am in Southern California. Los Angeles “County.”
I called my local “city” office and specifically asked “As a Notary Public, do I need a business license in order to conduct business?”
Answer: “If you are working out of your home, as a Notary Public, then yes, you would need a license. The license is needed for running a business out of your home. Please visit our website or register in person. The cost is $70.” 

So, in addition to being commissioned by the Secretary of State, I also need a license from the city to run my business from my home. ($70) On top of that, I need to register with L.A. County for my DBA. ($38) With the DBA, I need to run it in the newspaper for 4 weeks ( $50-$100), depending on the newspaper you use. Oh but wait. If I want to go LLC, that’s another $70 with the State, who also says I need a registered agent, which is another $50.
So, the answer to your question. Check, check and double check with whatever “city” you live in within your “County.”
Los Angeles County alone boasts 10 million people strong.
Each sub city within the county has their own set of rules.
** PS** For clarification, I am not running a business from my home where there’s customers showing up at my door etc (NEVER!)… it’s just the fact that you call yourself a"business" is how they get you…
So, it’s not the “State” that requires the " business license", it’s the city in which you live or are operating your business in that requires a " business license"
Just my two cents!