Do Guys know what's Activation key is?

An activation key is usually a series of numbers and letters that you enter after installing software. Activation occurs when the key is accepted over the internet by the publshing company's servers. Activation allows the company to check to see if you are using a licensed copy of the software. If the software only allows a single license on a single computer, the activation key serves to make sure that the software has not been activated a second time.

Failure of an activation key may prevent you from being able to run the software on your computer.