Just for the sake of saving yourself some money, and the time to take it to an Apple Store, you can clear things up yourself.
1) Backup the entire drive, however you do that. Time Machine, SuperDuper!, Carbon Copy Cloner, etc. Preferably two full backups on two separate drives.
2) Restart the Mac and hold the Command+R keys to boot into Recovery mode. When you can, choose Disk Utility from the menu bar. Erase the boot partition. Exit Disk Utility and choose to install OS X. You will now have a clean drive. Anything that may have been there will be gone.
3) Reinstall your third party apps only from their legal sources.
4) Manually restore your emails, photos or other personal data from the backup. Do not simply merge in a TM backup. If there was anything to get rid of, you'd only succeed in putting it back on the drive. Restore items selectively.