Get rid of it now:
It will do nothing but hose your system.
I also fell for the MacKeeper scam. The fact that it is off of a website and not from the app store really made it sketchy to me. I deleted it as soon as I opened it because it said I had over 100,000 system problems and the only way I could fix it was by buying the premium software. If I were you I would delete it and browse the app store for an antivirus. I have 2 antivirus programs that work amazingly. "iantivirus" and "virusbarrier express". You can also speed up your system with programs like "Ccleaner" and "Disk Doctor". Those programs delete all the temporary files and uneeded stuff that is hogging up space on your drive. They are also available in the app store. Hope this helped!