When purchasing Office for Business 365 Premium it indicates that it allows installation on 5 PCs and 5 mobile devices.  When trying to activate on a new laptop it will not allow it due to the key already being used.  I have not installed it on 5 PCs or devices.  How do I get it to activate it on the new computer?

Sounds that you've purchasing Office 365 Small Business Premium.

You can later login to their Microsoft account at www.Office.com/myaccount to manage your subscription, re-install their software, or install it on another computer or device. Once the new Office has been redeemed and activated, you will not need to use their Product Key anymore as they will access their Office.com/myaccount page with their Microsoft account to manage their product

Tony Chen
TechNet Community Support