Keyfinder is a free software that shows product key (CD Key) of Windows and other programs.
Number keys and serial numbers of Windows and other installed programs, are stored in Windows registry, and therefore can be recovered. It is possible that we want to retrieve a number key, and don't find the manual or email where it is stored. For these cases, we can use the following program that shows us the installed software's keys.
Keyfinder is very simple to use, so we just have to install and run it. After the first start, the first thing that is displayed is installed Windows version along with the serial number associated with the installation. In the left part of the window there's a list of the installed programs. Clicking on any one of them will show the registration information associated with that program.
This software can extract the keys and serial numbers of more than 300 programs such as Microsoft Office, Microsoft SQL Server, Winamp, Malwarebytes Anti-Malware, etc.
In addition to retrieve the license number of the Windows system that is running, we will also be able to recover the key of other Windows systems that are located in another hard disk or partition on our PC. So we just have to click on “Tools->Load Hive...” and select directory where other Windows is installed, so we can retrieve serial number.
At installation time, we should choose “Custom Installation (advanced)” and uncheck box labeled “Search Protect by Conduit”, because if we leave this check box selected, this will install an additional toolbar in browsers, which is considered malware, and can be very annoying for the user.