Do I Need a Business License Just to Sell Online?

Hi everyone! I started selling stickers and prints on Etsy a couple months ago. Super small scale, just a fun side hustle. Now I’m getting questions from friends about taxes and business stuff and I realized… I have no idea what I’m supposed to be doing.

Do I need a business license just to sell online? Should I register as an LLC or can I leave it as is for now? I’ve made maybe $400 total so I didn’t think it mattered but now I’m second-guessing myself.