Migrate win10 key to win11

Question

Hello,

Recently I have mounted a new PC with all new components and I have intalled Win11 in it, creating a local account.

I also have an older PC that currently has Win10 and is connected with my hotmail account.

What I want to do is use my win10 key in my win11.

I also want to stop using my win10 and will format my SSD (with win 10).

I have looked in my Microsoft Account, and the only device that I can see is my new PC, the old one is not showing.

Also, if I try to activate my win11, the device that appears on the screen to select has the one that I am using is my Win10 and not my Win11.

How can I migrate my win10 key to my win11?

Is there a way to do it, or do I have to purchase another license key?

Thanks