If it's about the key of an installed windows, you could run the QT from here and it will show you the full key in the private saved report.
QT v121 sets off defender messages for me, and the QT executable is deleted when I run it. Yes, I know, I could safely disable defender temporarily...
Have you tried taking a photo with your phone and zooming in? The total combinations available would be for 3 letters: 24 * 23 * 22 = 12,144. You could use slmgr /ipk XXXrest_of_key until a valid combo is found. I'm not sure how you'd script this tho...
Small correction: Beginning with Windows 8, there is one letter N in the key. Exactly one, not zero, not two or more.