Someone told that you need a MP3 license to encode MP3s and publish them. Is this true? If I make a recording, encode it as MP3 and put it on my website am I breaking the law?
No. You would need to purchase a license if you wanted to make a software program that encoded things to mp3s. If you purchase software to encode your mp3s, that software vendor should have obtained a license from Philips. You do not need to purchase a license on top of that.