Win10 free upgrade ends in less than 1 month. If you have upgraded, but need to re-hash your OS, unlucky, you'll have to pay.
My PC auto-upgraded a while back, but as I have my HDD partitioned (so only the OS is on one partition Q: (deliberately not C; for security attack reasons), Docs on one, Audio on another, Video on another, WIP on another, etc, etc
If I need to reload the OS, I'll use my Win7 Disc and revert to Win7.
Win10 has only caused me problems - only 1 monitor working (think I can fix this, it was reported as a virus?!?!?, but Norton found nothing), no bi-directional with printer (not yet tried 2 scanners or scanner/printer, no future support from Canon, Thanks!!!).
When I finally get p1$$£d off with it, I'll go back to Win7.
Laptop, still on XP, but will only ever let that go as far as Win7 (if able!!!, Vista capable, but never took it up).
Google for a woman in USA who got £7500 ($10000) in Compo from MS as they left her PC dawdling at sub-Baud9600 levels of performance, affecting her business, WITHOUT CONSENT!!!!