MAKCount: 866 — a Multiple Activation Key, so it isn’t one-per-person. That number is how many machines it will still activate and it only counts down.
Then slmgr /xpr to confirm it’s permanent. Works on Pro — on a Home install the key upgrades the edition first, then activates, and the machine reboots on the way through.
Open the Start menu and select Settings (the gear icon).
Go to Update & Security, then click on Activation.
Select Change product key under the edition upgrade section.
Type your 25-character Pro product key and click Next.
Select Start to confirm and let your PC finish the upgrade and restart.
Windows 10 / 11 Professional — MAK key with 866 activations left
!