Minecraft for win10 key on which account?

So there were times when you bought mc java edition mc for win10 for free, I just don't know which acc I set it up for. Can I find out which acc the key is on or how to reset it from the pc where i redeemed the key? Delete the mc account i have access

You can see on the Mojang page when you bought the accounts and deduce whether a key is included.

A key was there until mid-2018.