The smart way to do it is write up a business plan like jvgr says.
At the very least, talk to an accountant. They should really be the one to answer the license question. The reason you would need to get a business license is for tax reporting purposes.
If it’s just you working for your new company then you can technically operate as an independent contractor (which means you don’t need a license).
I’m sure you want to keep most of the money so in order to figure out what way you can do this in order for the government to let you keep the most money, you’ll need to speak with an accountant.
Good luck.