A friend of mine has a PC with Windows 7 Ultimate and he wants to upgrade to Windows 10 Home without reinstalling applications, the same way as Windows update. Is it possible, even if he has to change the serial number before the installation?
I had W7 Ultimate. The upgrade offered is to W10 Pro as stated in MS equivalence table.
Most applications will remain installed as they were before update. I only lost Adobe Acrobat Pro (which had an old invalid license) and Speccy (dunno why it got lost). The update process assigns you a new W10 license and activates it without your intervention.
UPDATE: The update can be done from a downloaded ISO (from here) but it does not let you choose between home and pro editions on the download. Anyway, keep the old W7 license key at hand (write it down or something) just in case.
Frankly, this question & your later comment are most confusing.
Is this just an XY Problem ?
Does he specifically want Win 10 Home, or do you think that is your solution because you have WIn 10 Home already & think you can save his data download requirement?
Either way - carefully work through http://windows.microsoft.com/en-gb/windows-10/media-creation-tool-install - get the media creation tool on your machine (presumably one without a limited data connection), create the USB stick by selecting "Create installation media for another PC." then run that created USB key on his machine from the USB stick.
Do not boot from it, double-click the setup.exe from his running system.
The end result will be an upgraded, activated Windows 10 Pro, as that is what his license allows.