Background
Two months ago, one of my cousin bought a Lenovo Ideapad 100 notebook with Windows 8.1 single language OEM preinstalled on it. The notebook uses BIOS key to activate OEM genuine license.
Yesterday, he asked me how to upgrade his license to Windows 10 without downloading the installation media on his side, since every attempt he had taken to update on his own from internet were failed/stopped abruptly at low percentage progress (his internet provider might be slow, unable to deal longer with large files). Then he want to lend my Windows 10 media disc (of course without key) by agreement.
However, I realize that the disc used on my early-upgraded PC is suitable for 32-bit version of Windows 7/8/8.1, while the target system to upgrade has 64-bit version. We're in a hurry because Windows 10 free upgrade offer will end 2 days later.
Problem Statement
On his remaining time to upgrade into Windows 10 license for free, I have these 3 alternatives to upgrade his current system:
Install/upgrade with Windows 10 32-bit version I already have (compromising his OEM tools and probably also his OEM key),
Obtain 64-bit version from Microsoft site on my side (I afraid the upgrade may not execute immediately before time limit ends, consider more than 2 GB amount to download a proper media),
Buy a 64-bit version disc from nearest store then use it on target system (costs some amount of money which I should avoid this as I could).
I prefer the first choice since it requires less time and effort than others, but how I can upgrade it with his embedded key to obtain Windows 10 license as soon as possible?
Any kind of suggestions will be appreciated.