I have the following scenario:

Windows computer, Windows 10 installed and activated on disk 0

Inserted disk 1

Installed Windows 11 on disk 1

Now I want to activate Windows 11 on disk 1, using the same product key as for Windows 10 on disk 0 on the same computer.

I do not have the key in plaintext. I am signed in to my Microsoft account on both installations, but on Windows 11 it doesn't seem to find and recognise the key.

What would be the next steps?