Talk to an accountant and a lawyer. Register something, probably a simple LLC would do but no generic advice is possible on exactly what and where to register -

Talk to an accountant and a lawyer. Register something, probably a simple LLC would do but no generic advice is possible on exactly what and where to register - it depends on your personal situation. Do some business for a year. There is nothing like learning by doing, none of us have any idea what your skillset is and how you're making money to give you advice. Why do you think you need investors at this stage if you're already profitable?