Windows 10: Can I buy windows 10 from microsoft and activate it on a different PC?

So my grandad has win7 and as its coming to the end of its life (rip) he has asked me to update him to win10. I want to be able to install it for him as quickly as possible when we get up there so we have time to do some other stuff. If i buy windows 10 home from the microsoft store on my own PC at home, can I install it on his PC? or does it make me install it on mine? Will it just give me an activation code or what?

Sorry for my ignorance but I've only ever used boxed windows before
Any help is very much appreciated
Thanks <3

:)

 

DOWNLOAD WINDOWS 10 NOW - Upgrade and ISO direct from microsoft

Click to expand... Yeah I went to that site, why do I need to buy a key?
I won't buy a key, stupid.

I'll revert back to windows 7 then.

When I still was on windows 7, about a year ago I added 4GB extra ram which is a total of 8GB now,
is that causing the problem?

 

DOWNLOAD WINDOWS 10 NOW - Upgrade and ISO direct from microsoft

this search might help you https://www.google.com.au/webhp?sou...o+to+get+it+activated+windows+10+blocked+keys

From http://windows.microsoft.com/en-us/windows-10/why-activate-windows-10

If you upgraded to Windows 10 for free and ended up in a non-activated state, try following these steps:

• Go to Start
  
  , then select Settings > Update & security > Activation.
• Select Go to Store, and check to see if a valid license is available for your device. If a license isn't available, you'll need to buy Windows from the Store.
  
  Note
  • This only applies if you haven't made changes to the hardware for your device.

or you could hack it with a crack but please note this is always risky and you don't know what's in the hack

 

Windows 10 Activation (Insider)

This kinda sucks. However, if one is upgrading from a retail W7/8, then it should activate on different hardware, with possible phone activation required if it's been over 120 days or whatever the timeout period is now since the last activation. Remember to erase the copy on the old hardware, of course.