Pace Anti-Piracy is the name of a company. According to their website they have "...over 14 years of field-proven experience in delivering anti-piracy solutions. Hundreds of world-class software companies, from Adobe to Corel to Disney, trust PACE to solve their anti-piracy problems." Source
They have two primary products. The first is called iLok and the other is InterLok Pro. In the left column of the above source is a Contact link. You might be able to get the tech support people to tell you how to remove all traces of their product. If they won't help, and if you know which product you installed / uninstalled, you could try using the start menu search function to see if you can find any remaining files or folders. Or you could use the registry editor (regedit) to find leftovers.
I guess my only question is what prompted you to install this? (Assuming you installed something from this legitimate company and not some rogue malware using the same name.)