Yes, you can use it on a Windows OS.
Yes, you can use it on a Windows OS.
You can use your Windows 7 key on another device temporarily. The same product key will work for installation. Turning the laptop on and off during use is fine as long as you follow local laws. Even though it might be considered misuse, it’s not inherently illegal if done responsibly. Let me know if you need more details!
It's against the rules to discuss this further. Using a product key is required for each item. I won't provide more information on this subject.
Using a license on a laptop doesn't allow reuse on a desktop. This is the way Windows 7 and later keys function. It's possible to fix it by contacting Microsoft, but I'm unlikely to help in this case because you'll also need a laptop to use it.