Back up the entire system (OS and all) and partition(s) holding your project, run a sysprep on them if possible (so they’ll boot up if restored to a different computer/configuration in the far distant future), and store them in a safe climate controlled place. Either image things in a way that EVERYTHING YOU NEED (OS, DAW, sound-card drivers, plugins, EVERYTHING) can be restored exactly as It was when you finished the project, or simply clone then swap out and use brand new drives on a regular basis (keeping your old drives as backups).
This way, if you ever try to open an ‘old’ project in your latest and greatest all up to date DAW Workstation and it’s not cooperating to satisfaction, you can always go pull the hard drive(s) with everything you were using at the time and stick them back in the system.
I can’t afford to get new SSD system drives on a regular basis (but I do tend to go with smaller system drives of 1tb or smaller and change them out every year or so), but large bare bones platter drives are cheap enough these days to keep easily restorable partition images and regular system back-ups on a fairly regular basis. If you do enough volume it might even be worth it to look into an enterprise class tape or optical media back-up solution.
If it’s a big successful project that’s really important to me…honestly, I clone to new drives, run a sysprep on the old ones, and store them in a safe place.
in the least it’s always a good idea to either start with a fresh drive, or clone images of everything before applying lots of updates/upgrades to a workstation.