You don't need a business license to sell. The only thing you really need to do is pay tax on your income.
Be careful before you contact someone like the SBA -- there are few people there who will understand what you are trying to do. They will treat you like someone who wants to open a local computer retail store (my experience) and push a bunch of business support people (accountants, lawyers, other white-collar losers) who want to be paid to do things you don't need.
If you're in the US, get online and sell your software.
specifically, bschmidt1962's comment, disregarding the team aspect