Update a jailbroken iPod ?

I had my iPod jailbroken and I wanted to get rid of the jailbrake, so I decided to update it to the newest version 4.2.1. It kept ALL the apps I got for free, and kept all my music. I thought it would erase everything so I can start new. Does this mean that ALL the apps I got for free will get paid for automatically, or what? 'Cause if that happens...I'm screwed.