Office is not just Office, especially when it comes to choosing the “right" package. Basically, there are two version “types" to distinguish: On the one hand the subscription version Office 365 and on the other hand the possibility to buy a version once. This option only applies to Office 2016 and Office 2019, where the one-time purchase of the software purchases a perpetual license that does not receive feature updates. Only updates for quality and security patches are installed. This is not the case with Office 365, which provides permanent automatic updates.
So there are a few things to consider when choosing your Office version. However, if you are interested in stable updates, you should decide for the second variant. If you are about to decide whether Office 365 or Office 2019, this article might be interesting for you.