You can download an ISO and burn it to a CD or DVD and then you “permanently” have the source media.
Interesting experience doing this. I upgraded my laptop to Win10 to see if I'd like it. Looked good.
Then I decided to swap the laptop harddrive for an SSD. Did a clean install of Win10 from a CD. The install wouldn't accept the prior License key. I skipped that part and proceeded to the privacy settings. I tightened them up and it took me back to the license key. Dead loop. So, I tried allowing the default privacy settings and behold, it allowed the installation.
When you add another user, it requires their email address. The whole OS appears to be written by NSA to spy on us. Since the default spy setting allows them to know what I type, I'm curious where the key logger program is.