Question about upgrading to Windows 10

Can I use the Product Key from another eligible laptop to upgrade my currently non-eligible PC? Will this void the license for the laptop or simply void it's eligibility for an upgrade in the future?

Good question, I'd like an answer also. 30 minute bump because pfffft.

I'm guessing yes, providing it's not an OEM copy, as you can move them about PCs with no trouble apparently.

Yes provided you havent already activated the eligible laptop as it is licked to a hardware ID once it activates

I found a guy on reddit who buys keys for operating systems and appications in bulk and then resells them, could I use one on the upgrade tool even if it's not the same as my current key?

You can do an in-place upgrade, meaning, download the ISO, burn to flash drive. upgrade the machine while it is booted into the old OS. after the upgrade verify it has been activated. The keys for all free upgrades are the same across the board. The activation is tied to the hardware ID. The final key for Insider copies are not the same

This whole upgrade process is kind of shit, I upgraded my 8.1 pro copy, waited for it to be activated, did a clean install and they blocked my key.

Called into the phone line activation and was flat out told I am not allowed to do a clean install, to reinstall a different OS at this time.