It gets regular updates. There is a version that you can just buy once, but it only gets updates for (I think) a year and then you have to buy a new one whenever you want an update.
The problem with this is: Office is pretty much feature complete for most uses, people don't need regular updates to their word processor. Microsoft has even removed quite a few features since the Office 97 days.
Retail Office gets updated about every three years. That's plenty, buying a subscription for Word seems hardly worth it.
Retail Office gets updated about every three years. That's plenty, buying a subscription for Word seems hardly worth it.