Using on premise AD accounts not Microsoft accounts

We are considering Office 365 Pro Plus just for Office. But just to use Office on premise, because it's less expensive than perpetual licensing. SharePoint and Exchange will remain on premise and we do not want to use OneDrive for Business - no cloud storage at all anywhere. We plan to deploy and update using on premise method. Do our users still need a Microsoft account for activation and the "every 30 day" check, or can we somehow set up their AD account? If must have Microsoft account, how often will users be forced to log in and why?

Thanks,

Joan