Now that you have your business license, if you want to stay on the up-n-up, you'll need to report your income (net profits) and you'll need to pay sales tax back to the state (in states with sales tax). If you're low-key, then you can probably do a Schedule C by yourself, but if your business starts to get big, then you'll have to pay an accountant. I used to sell heart rate monitors, but after paying the accountant to do the small business tax forms, I'd spend more than I made.