How to get product key of old OS (Win 7) after upgrading to Win 10?

Cliff S said:

Kari, so that means, I can just delete both my Win7(from laptop) and Win8.1(desktop) system images, because they're "done for" now. Not that I ever plan on going back:)

You can do that Cliff but as Kari says there is no point.

I did use slmgr /upk <xxxx.xxxx.etc> to remove one license from broken laptop before I moved it to a VM.

I try to be honest (that is the only reason I did it). I turned on the old 8.1 laptop and it said "not activated" but I only used it to get some files I forgot.

It is up to you how honest you want to be.

On this site it seems mentioning using an invalid MS license is interdit but mentioning torrenting movies/films is fine - even if it is with a "nudge-nudge, wink-wink" as some VIP's do.

Personally I disagree - I think if you want it you should pay for it - but it isn't my business either way.

Kari, NavyLCDR, I had exactly the same question. I have not tried out, but I also was not sure, whether it would be possible to use the underlying Windows version after a PC had been upgraded to Windows 10.

So you, Kari, have tried and your result is that it is not working. This confirms what I had feared (and what I was told would be wrong).

However, there is one question, which is still open:

When you upgrade to Windows 10, Microsoft gives you this 30 day period in which you can roll back to the previous OS. When you, Kari, say that the old licence can no longer be used, does that then also mean that you cannot really go back to the old OS, as Microsoft would then no longer activate it as well? I think people are using this rollback feature and (apart from a few bugs) it is generally possible to go back.
How does that fit to your observation that the old OS can no longer be activated?

(And now don't tell me that activation status would somehow be preserved so that no new activation is needed. This does not help; one might still want to change some hardware so that a new activation becomes necessary. Then this is the point, at which you would be screwed, if the activation server would no longer activate your licence.)

Joergi said:

Kari, NavyLCDR, I had exactly the same question. I have not tried out, but I also was not sure, whether it would be possible to use the underlying Windows version after a PC had been upgraded to Windows 10.

So you, Kari, have tried and your result is that it is not working. This confirms what I had feared (and what I was told would be wrong).

However, there is one question, which is still open:

When you upgrade to Windows 10, Microsoft gives you this 30 day period in which you can roll back to the previous OS. When you, Kari, say that the old licence can no longer be used, does that then also mean that you cannot really go back to the old OS, as Microsoft would then no longer activate it as well? I think people are using this rollback feature and (apart from a few bugs) it is generally possible to go back.
How does that fit to your observation that the old OS can no longer be activated?

30 days is only because cleanmgr.exe deletes windows.old etc. I have restored back many many times since July.

And have you, halasz, actually done a new activation of that old OS? If the old activation status was just retained (I believe it is, after all the rollback basically just gives you back your old system), then you don't really know, if it would activate again, as there has been no need to talk to an activation server. It would just still be activated, not again. That is a difference!

Basically I understand what Kari is saying, that the old OS was no longer activatable, but I don't understand how that fits to that other people could still use the previous OS without problems.

Kari said:

Could you tell me why?

Kari

Yes, I can tell you why. Many members here run dual boot with Windows 10 on one partition and their old operating system on another partition. Violates the EULA, sure, but the old product key is in no way invalidated.

Second. I have restored a laptop that had Windows 8.1 factory installed with the product key stored in bios back to Windows 8.1 after upgrading it to Windows 10 and after the 30 day revert period. Works just fine. Why? Because I want to sell the laptop to someone in factory fresh condition without a trace of my Windows 10 stuff that might have carried over to it via Microsoft account syncing and the Windows 8 product key stored in bios is just as valid as it always was.

Just like my Windows 7 family product key that is still valid that I used to install Windows 7 on a second partition on my desktop computer to try to solve a hardware driver issue I was having.

You statement that the previous OS product key is invalidated either the minute Windows 10 activates or after the 30 day reversion period just isn't true. But if someone wants to believe you - it's their loss. If someone wants to go back to their previous OS and they try their old Product Key and it didn't work because your posted nonsense was true - well all they would lose is a couple hours of their time.

Joergi said:

And have you, halasz, actually done a new activation of that old OS? If the old activation status was just retained (I believe it is, after all the rollback basically just gives you back your old system), then you don't really know, if it would activate again, as there has been no need to talk to an activation server. It would just still be activated, not again. That is a difference!

Basically I understand what Kari is saying, that the old OS was no longer activatable, but I don't understand how that fits to that other people could still use the previous OS without problems.

I have done clean installs of both Windows 7 and Window 8.1 previously upgraded to Windows 10 and they both activated just fine. Windows 8 product key stored in bios, and Windows 7 product key entered manually. Windows 8.1 was restored using ISO downloaded with the Windows 8 media creation tool and Windows 7 Home Premium was restored with the Microsoft genuine DVD from the retail package with the COA sticker.

Microsoft never has invalidated previous OS product keys upon upgrade, and they still are not. It is only the EULA that is violated if the previous OS product key/license is used at the same time the resulting upgrade license is being used, but Microsoft has never really enforced that by blocking product keys, nor are they currently enforcing it.