I have a Money Service Business license from FINCEN.
Then you can use localbitcoin.com with no issues with the Feds, as stated above there is the state. But assuming either:
They don't have a license in your state (Texas and others).
They say you don't need a licence in your state (Colorado and others).
You went ahead and also got the state license (New York, and others).
You are
theoretically good to go and can conduct as much business as you want to using localbitcoins, your own web site, storefront, whatever.
Of course, now that you have the proper licensing you need to play by
all the rules written for those who have said licenses.
But I suspect you already know all this....