There are two ways to purchase Microsoft Office, either as a "one off payment" or via Office 365 and a subscription. You get a lot more with the subscription and you also get regular updates.
One trick I recently discovered via a colleague/friend is that if you hold the Control key down whilst accessing the context menu of the Outlook system tray icon you get some extra options in the menu, one of which is "Connection Status..." which can help diagnose issues or allow you to see what you are actually connected to.