How do I find the product key for Microsoft Office 2013 which is activated in my system ?
`` I had pre-installed Office 365 on my Laptop . I tried some crack key and it worked a month long . Now , I want to activate it by purchasing an authentic key from Microsoft , but when I am trying to activate the product over Internet I am getting the error '' `` Product Key is not valid '' '' . What can I do to solve this ? ''