Each version needs a different activator, so if once failed to activate Windows 7, do not try to find a working product key. Simply download another activation software and try again. You are sure to succeed. Using an activator software has many advantages over using a license key.
There is no difference in the activation methods. The only question is how to do it in a simple way. If you find a key in the public domain, it can be used by someone else at the same time. Over time, Windows will find out about this and lock the key. If you plan to extend your trial period, this method will help you extend your license to 120 days. Thus, activating Windows 7 with an activator looks much more acceptable.
Download the actual activator windows 7 you can from the official website.