Eeeeks. Of course you should consider first.
I personally don't know of a business where you have to have a license first.....and if there is, what are they gonna do? arrest you
Must have been before your morning coffee, but how about doctors, pharmacies, contractors, construction, lawyers, etc
You should check at the local/city/county, state and federal level any license requirements and make sure you have that squared away first. Contact each government office based on where you live to find out if any licenses are needed and if so the requirements.
The current owner should be able to explain to you any requirements, but best to double check he/she is accurate.