Office 2007 Used Too Many Times *URGENT* How Do You Enter A Product Key On Microsoft Office 2007?

*URGENT* How do you enter a product key on Microsoft Office 2007? - office 2007 used too many times

Recently formatted my laptop and when I start Microsoft Office, which had asked me a product key, I am the original key, so I have a line. This was "much used too often and now I do not know how to enter a new one. Do you have a ratio of 25%, due Friday, and I can not, because this shit started. HELP PLEASE!