Office365 ProPlus: Activation

Activating Office365 ProPlus:

Unlike a typical Microsoft Office install and activation, Office365 ProPlus automatically activates when you Install it from the Office 365 online Portal. To keep the installed programs activated, you must connect to the internet and sign in to Office 365 every thirty days. If you go past the thirty days, your account will be put into Reduced Functionality Mode. 

Referenced from: Microsoft