I bought optimizer pro from you but the key wont work

Fixya does not sell PC Optimizer Pro, nor does it endorse it. This is a registry cleaner program, which is promoted via other free downloads, and once installed it claims that several issues were been detected on your computer. If you try to fix these problems, PC Optimizer Pro will state that you need to buy its full version before being able to do so.

PC Optimizer Pro it\'s technically not a virus, but it does exhibit plenty of malicious traits, such as rootkit capabilities to hook deep into the operating system, browser hijacking, and in general just interfering with the user experience. The industry generally refers to it as a "PUP," or potentially unwanted program. I would highly suggest that you uninstall this dangerous app and seek your money to be refunded.

There are many websites describing how to remove it, like this for example:

http://malwaretips.com/blogs/pc-optimizer-pro-virus/