There are many times that you added a wrong key to Office 2013 or you need to change the key.
Open Command Prompt as Administrator
For 64-bit version of Office 2013, go to: C:Program FilesMicrosoft OfficeOffice15
For 32-bit version of Office 2013, go to: C:Program Files (x86)Microsoft OfficeOffice15
View the Current License
cscript ospp.vbs /dstatus
Remove a License
cscript ospp.vbs /unpkey:<last five characters of product key>
Re-activate MS Office 2013
Open one of the MS Office 2013 applications and reactivate the by providing your sign-on ID or Key
Pantelis Apostolidis is a Cloud Solutions Architect at Microsoft and an ex Microsoft Azure MVP. For the last 15 years, Pantelis has been involved to major cloud projects in Greece and abroad, helping companies to adopt and deploy cloud technologies, driving business value. He is entitled to a lot of Microsoft Expert Certifications, demonstrating his proven experience in delivering high quality solutions. He is an author, blogger and he is acting as a spokesperson for conferences, workshops and webinars. He is also an active member of several communities as a moderator in azureheads.gr and autoexec.gr. Follow him on Twitter @papostolidis.