to anyone like having trouble activating here what you need:
How to change the product key of Microsoft Office?
Click on the button to open the Start Menu. Now, click on the Control Panel and then click on Programs (Uninstall a program), and finally click on Program and Features.
(Windows XP users: Start > Control Panel > Add or Remove Programs.)
From the list of installed programs, find Microsoft Office Professional Plus 2013 . enter this key:
select it and then click on Change.
From the newly opened dialog box, select the Enter a Product Key option, and then click Continue.
Type your new product key
and check the option that says Attempt to automatically activate my product online to automatically activate your Office 2013 .
Now click on Continue and then on Install Now.
that’s it good to go.