When you say "throw away Windows 10 Pro subscriptions", what do you mean exactly? Do you mean just not using them (by running Linux instead), or do you think if you install Linux you'll lose the licenses?
If the latter, the activation/product key is (usually) stored in the firmware of the machine, so you can reinstall Windows in the future and it'll automagically be activated with Windows 10 Pro again (you don't even have to input the product key). To check, follow this guide, and run this command in an Administrator-level PowerShell:
wmic path softwarelicensingservice get OA3xOriginalProductKey
If the command returns the product key then you're good to go.
When you say "throw away Windows 10 Pro subscriptions", what do you mean exactly? Do you mean just not using them (by running Linux instead), or do you think if you install Linux you'll lose the licenses?
If the latter, the activation/product key is (usually) stored in the firmware of the machine, so you can reinstall Windows in the future and it'll automagically be activated with Windows 10 Pro again (you don't even have to input the product key). To check, follow this guide, and run this command in an Administrator-level PowerShell:
If the command returns the product key then you're good to go.