Some business users may have put in the wrong key when the first installed Office 2010. Some software pirates may have been caught. Whatever your reason, changing your Office 2010 Product Key is easy, here’s how you do it:
I consider Microsoft Word to be the father of all Office products, so I advise opening Word. But if you didn’t install Word, any Office product ought to do, such as Excel, or even Outlook. Click on the File menu in the upper left. Then select Help. To the right, you should see that your product is already activated – if it isn’t, this is where you can activate a new install, or change your key of an existing install. In order to avoid the need to reinstall your Office product, your product key should match the current version of Office installed (Home and Student, Professional Plus, etc…).
Similar steps can be followed in Office 2013 to activate or change your product key, should you need to.