qqp question1: How do I find the product key for Microsoft Office 2013 which is activated in my system? question2: "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?"