Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
The subscription model was Microsoft's announced plan when Office 2013 was released with the caution that it would be the last version available to buy outright and future versions would be subscription only. That announcement accomplished what MS probably wanted: Many, many users of Office 2007 and 2010 rushed to the store to buy Office 2013. Then, contrary to the 2013 warning, 2016 came out as a buy or lease version, just like 2013. And many people convinced that 2016 would be the last, bought it.
When Adobe announced Photoshop CC as a subscription product, users of Photoshop CS5 and earlier, rushed to upgrade to CS6. I already had CS6 and have stuck with it even after CC was released in 2013. My wife subscribed to CC for $10 a month. Since then, she has paid over $500 to Adobe for several versions and subversions, and around half the updates are bug fixes of earlier versions. Adobe went to the subscription model because people were not buying their upgraded versions. Why? Because their new versions were not sufficiently improved to warrant the $200 upgrade price. Some of us wondered where their motivation to improve would be when they collected money from users just for using the product. Read the release history on Wikipedia, and you'll see that the doubters may have been right.
Will that be the case with Office, once it is a subscription-only product? I'd bet on it.