Wondering what happened to the free upgrades from Windows 7 or 8/8.1 to Windows ... The difference is that with a retail license, you can transfer the license key to a different PC later on.
Another thing worth noting is that you still need a genuine Windows key to activate the operating system (older Windows 7 and 8.1 keys should work just fine). Finally, always mind the potential ...
Windows 10 is installed thousands of times a day on computers both new and old. But without a receipt, how do you prove that you actually own Windows? That's where your product key comes in.