So having worked in a few IT departments, I’ve noticed that ones where the general culture is “let’s buy this off the shelf product and a support contract” tend to have a lot more dealing with issues while sitting on their hands and blaming the vendor whereas the departments that are more hands-on and take the approach of “let’s find the right solution and make it work whether or not we can get the vendor support we’d like” tended to have more robust systems, but also more outages due to their own internal errors

So like most decisions in both business and IT it comes down to risk tolerance. I think in the context of your choice of Office suite that risk level is fairly low. Libre Office is an office suite which installs onto the client PC and has minimal integration with outside servers. Its extremely easy to uninstall and reinstall an earlier version if you identify a problem while rolling out an update, and it’s extremely easy to hold a version and not update (which of course comes from security risks, but again, those are not terribly significant compared to other IT contexts)

The main thing in this context that a vendor support contract would provide is the ability to deploy developer resources that are already familiar with the codebasd on a bug if you encounter a problem that’s significant enough. In the case of open source software like Libre Office you get the added benefit of being able to simply spend money on developers and maintain a fork if the upstream project is giving you enough trouble too.

The bigger risks where you will really want a support contract is on the server and network side, because those are much more critical when an issue does arise, may require restoring from backup to rollback and will often have contingency plans as expensive as maintaining warm/cold spares and separate failover regions and hot spares