Microsoft Office for Mac — that is, the suite of applications that includes Word, Excel, PowerPoint, Outlook (Home & Business edition and 365 subscription edition only), OneNote, Teams, and OneDrive — receives a new update monthly. The current version in July 2021 is version 16.50, next month will be 16.50, etc.

As of July 2021, you can subscribe to the Office software via the following Microsoft 365 plans:

• 365 Personal: use on five computers by one person, $69/year
• 365 Family: use on six computers by up to six people (they can have their own Microsoft logins), $99/year
• 365 Apps: business plan with per user pricing at $8.25/month
• 365 Business Standard: per user pricing that includes both Office software and Exchange email hosting at $12.50/month
• a different 365 business plan (there are many) that includes both software and email hosting, with per user pricing

You can also buy the Office software outright, as a one-time purchase:

• Office Home & Student 2019, one computer (but sometimes 2-3 works), $149
• Office Home & Business 2019, one computer (but sometimes 2-3 works), $249

If you buy it as a one-time purchase, it’s mostly the same, but:

• You don’t get Outlook if you buy the Home & Student version; you’ll need the Home & Business version
• You can’t customize the “ribbon” of icons across the top of the screen (this limitation is truly bewildering, and unique to the Mac edition)
• You don’t get access to the iOS/iPadOS versions of the apps
• You don’t get OneDrive (Microsoft’s version of Dropbox or Google Drive) storage
• You get monthly updates for three years after the product’s original release date, after which you’ll be “frozen” on whatever monthly version it’s at; and then you’ll get monthly security and compatibility updates for that frozen version for two more years, and then those will stop too. So, the later you buy Office after the original release date, the shorter a shelf life it has in terms of updates. You can keep using your frozen version indefinitely, but if it becomes incompatible with a future version of macOS, you’ll need to again buy or subscribe to the current version of Office. At the time of this writing, it’s probably not a good time to buy Office 2019, because it was introduced nearly three years ago.
  • For example, Office 2016 was released as a one-time purchase in September 2015. If you bought Office 2016, you got monthly updates until you were “frozen” in August 2018, at version 16.16, while subscribers got to go on to version 16.17, which also became the start of Office 2019. Security and compatibility updates for Office 2016 continued monthly for two years starting with version 16.16.2, until October 2020, when version 16.16.27 became the very final version.
  • If Microsoft repeats this pattern, then in August 2021, version 16.51 will become the last version of Office 2019, and then version 16.52 will become the first version of Office 2022 (though, breaking with tradition, it appears it will be called Office 2021). Then buyers of Office 2019 will receive monthly security updates for two years, in the form of 16.51.2, 16.51.3, etc, until topping out around 16.52.27 in October 2023.
  • This means it’s probably better to not to buy Office 2019 right now; I would subscribe for a few months if I needed it now, then buy Office 2022. (Or I would just keep the subscription so I don’t have to think about it.)
  • (Based on comments in a conversation I started on Microsoft’s support forums, receiving any kind of feature updates at all for the one-time purchase is unique to the Mac edition of Office; the one-time purchase Windows edition is feature-frozen from the outset, so there is no guarantee Microsoft won’t apply the same policy to the Mac edition at some point. But they haven’t so far.)