One can use Microsoft Account for everything you do with Office. If you use a Microsoft service like Outlook.com, OneDrive, Xbox Live, or Skype, you already have an account. With Office setup 365 Business Premium and Premium Security plans, you can install Microsoft Office applications on up to five computers, per user. Sign in Create a new account. Already entered a product key and looking for your software? Install from Office.com/Setup, you can ask for support Our team of technicians will resolve the query either manually or remotely.