"That key can’t be used to activate this version of Windows" when I used my previous Windows 8.1 pro keys on the new clean installation Windows 8.1 pro

I bought this laptop which has windows 8.1 pro installed on it. Then I upgraded this laptop to Windows 10. Yesterday I decided to reinstall Windows 8.1 by using media creation tools, but when I key in the previous Windows 8.1 product key, it says "That key can’t be used to activate this version of Windows". What should I do?