hello @Hesky even though some codes have a validity period, a certain user can use it. For example, like the first thousand people. But as our dear moderator @MashaPS said, I recommend you to get support.
I already contacted Google Store support. They checked the code was inactive for some reason they didn’t know. They asked me to contact Google maps support, they said because the promo code was originally issued by Google maps team. I then contacted Google maps support who then directed me here, they said because the promo code was for local guides. And now you want me to go back to Google stores again. I felt like I’m just getting kicked around without getting any actual help with the actual problem.
This is the screenshot of the response I got from Google store support case.