The change to a preactivated OEM version is well discussed. So that's true.
About the restore media. ALL Dell machines over the past decade have some procedure that Dell documents to create restore media. There has NEVER been Dell document to create OS CD/DVDs so I want to be perfectly clear that OS media and Restore media differ. Some folk need that called out.
Yes, a lot of folk ignore the need to create such media and today I think such costs about 50USD on average to order up a set or a memory key with the restore system.
Bob
Hopefully I won't be one of those frequent questioners, here. I just have one last confusing bit I want to share.
I took my laptop in to get the OS reinstalled. I kept getting "No boot device found" errors. For some reason the OS was wiped and it is yet to be determined as to why or how. Now I turn on my laptop, it functions as it used to, but I keep getting prompted to activate my OS after log in. My laptop NEVER CAME with an OS disk/product key. The shop that sold me my laptop confirmed it, saying the key was programmed in during manufacturing. No new Dell Inspiron 15-3521 (my type of laptop) will ever come with a disk.
So, do I just ignore it as a slightly annoying obstacle? (I guess I can do that) Or is this a bigger issue that needs fixing and how do I go about doing that?
Thanks.

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