How do you want to reinstall Windows?

I bought my sister a laptop and would love to surprise her. Would like to reset the pc now, but there comes this dialog window. Unfortunately, I'm not familiar with Windows because I only use MacOS. If I choose "local reinstallation", do I have to buy a new product key?

With a new installation you always need the Windows Key. If you still have a key, you can use it again, otherwise you will have to buy a new one. To get cheap on sites like mmoga.de or kinguin.net

Since you are talking about a new installation, in my opinion you do not need a new key if Windows was activated before.

OK? If I don't have the key, can't I just reset my laptop like I do with MacOS?

If you just want to erase all the data, you could simply format (erase) the hard drives. Then all data is deleted.

I just looked again, apparently you don't need the key for a new installation. So it should work without problems.

Create a boot stick (instructions on the Internet) with Windows 10. Then you do not need to buy a key.

I just had the key announced with a software… So I think it can be done that way… What do you think?