How to upgrade 1511 from Home to Pro?

Darren -

I am testing this now on a laptop that came with 8.1 Home embedded and 10 Pro entitlement, using both Media Creation Tool and Tech Bench  ISO download and will get back to you with what I find. 

 In Media Creation tool did you tick the box to "Create Media for another PC" and then uncheck the box to "Use the recommended settings for the this PC?"  That latter setting likely scans the OS you're using to confirm and force its version.   But they are contradictory.

I do not think the installer scans the BIOS for embedded Product Key, and haven't seen that it even activates from old OS Product Key in v.1511 until after install when/if you introduce it into the Change Product Key box as per the 1511 FAQ in Activation in Windows 10 - Windows Help .

Yes, I selected to create media for another pc and then unchecked the box to use the settings for my current pc.  I then created a usb installer with both the 32bit and 64bit versions.  I used that installer to upgrade my 32bit tablet, then did a clean install on my 64bit laptop (dual boot Home and Pro).  The problem came when I got to Pro and only had Home after the install with no apparent way to get it back up to Pro.

I have no doubt that the installer is scanning the BIOS for the key.  That was my initial impression even before I found the statement from Microsoft saying it does exactly that.  Why do you think it doesn't scan it when Microsoft themselves say it does?  I assume you read the very last paragraph of the section about activating with a Windows 7, 8 or 8.1 key in the expandable list at the bottom of the page you link to.  That paragraph says that on embedded systems the product key is verified during setup and then the appropriate edition will be installed.  It plainly says the embedded key is scanned during setup, not during activation, and then even clearly says that's what determines the version that gets installed.  The point of activation is too late to determine which version gets installed, so if the embedded key determines that, as that paragraph says, it must read that key before it begins the install.  If not, everyone would be getting the Home version and using another key that qualified for Pro would always be an after-the-fact upgrade - and you've already said that can't be done.  Surely that's why the installer is not giving me an option and is not asking me for a key - because it already scanned the embedded Home key and therefore is automatically installing Home based on that key.

Darren -

I am testing this now on a laptop that came with 8.1 Home embedded and 10 Pro entitlement, using both Media Creation Tool and Tech Bench  ISO download and will get back to you with what I find. 

 In Media Creation tool did you tick the box to "Create Media for another PC" and then uncheck the box to "Use the recommended settings for the this PC?"  That latter setting likely scans the OS you're using to confirm and force its version.   But they are contradictory.

I do not think the installer scans the BIOS for embedded Product Key, and haven't seen that it even activates from old OS Product Key in v.1511 until after install when/if you introduce it into the Change Product Key box as per the 1511 FAQ in Activation in Windows 10 - Windows Help .

Create Windows 10 Installation Media for Pro version   to do the preferred Clean Reinstall Windows 10 Upgrade.

Leave the Product Key blank to skip Next and Do this later during install. Afterwards use your WIndows 7 Professional retail or Anytime Upgrade key to activate as specified in the Version 1511 FAQ section in Activation in Windows 10 - Windows Help.

The OP who started this thread was trying to change from WIndows 10 Home to Pro by inserting a Windows 7 Pro Product Key but this is not supported as the only way to upgrade from Windows 10 Home to Pro via the link to Store in Activation settings to gain Digital Entitlement to then own both versions for the life of the PC,  or to use a Windows 10 Pro Product Key. 

So since you can point out what I did wrong you obviously have a bit of knowledge about how it works, so why don't you tell me how to do it correctly?

You say "create Windows 10 Installation Media for Pro version" but as of 1511 there is ONLY ONE installation media.  There is no longer a separate installer for Home and Pro, with them now sharing the same ISO.

And then you say "leave the product key blank" but if you have an embedded key it doesn't ask you for a product key.  Even MS themselves say the installer will choose the version (Home or Pro) based on the embedded key.  That being the case, how do I get the other version to install?

The 5th item down on the list of activation methods is the option I intended to use, in the event the activation wasn't automatic (as it was on a previous clean install of Pro):

You upgraded to Windows 10 (Version 1511 or higher) and activated it using a Windows 7, Windows 8, or Windows 8.1product key.

So how do I do that?  My Windows 7 key is for Ultimate, but the installer will NOT allow me to install the Pro version of Windows 10 because my system also has an embedded OEM key for Home.

The same page that you reference is where MS themselves say:

On some devices that came pre-installed with Windows 8 or Windows 8.1, the product key is provisioned in the device firmware. On these devices the product key will be verified during setup, and then the appropriate edition of Windows 10 will be installed.

So again, my original question still stands.  How do I install Pro and activate it with a Win 7 Ultimate retail key on a system with an embedded OEM Home key, when, as the above MS quote says, the edition that gets installed is determined solely by the installer based on the embedded key regardless of any other key that I may possess and want to use?