Do I need to reactivate Windows after reinstalling on the same computer?

Question

Windows

1. As I understand it, after a clean reinstallation of any Windows (XP, 7, 8, 10 - it is important for me to know for all these versions) on the same device, activation does not fail, and the key does not even need to be re-entered? Or before reinstalling, you need to somehow untie Windows from iron, and then re-enter the key?
2. I had a licensed Windows 7 on my computer, which I upgraded to 10. Will I need to reactivate 10 if I reinstall it?

Answer 1

1. Yes, this is a mandatory procedure, just enter your key and everything will go automatically.
2. After updating, Windows 10 generates a new product key that you can use to clean install and activate. Read more here .