I am about to do a security wipe and I was wondering...what will happen to my applications that I have purchased from blackberry app world? How am I supposed to get them back without paying for them again? Because I am pretty sure when you back up your blackberry on the computer, it does not back up applications.
In the OS versions im running (5.0), you're given the choice to wipe personal data, 3rd party applications and media card - all independent of each other.
If you choose to wipe personal data, you may lose registration information for 3rd party applications however, they will remain installed. Wiping 3rd party applications will completely erase them from your device, requiring you to download, reinstall & re-register.
1darrick's explanation for backing up 3rd party apps works as well however, I've had mixed results upon restoration (though many MANY users have had great experiences with this method).