We have a strange problem. My son can play Minecraft on his PC without any problems. Also bought the full version. But the demo only works on my wife's PC when he logs in. With my wife's account data, this works flawlessly on her PC. Where can I make settings so that he can play on both devices (of course not at the same time)?
Sorry, but somehow I can't quite make out your question:
Will the same account used to purchase Minecraft be used on both PC devices?
All of our 3 accounts were bought on my PC via the mojang homepage. Minecraft works on my son's PC. Minecraft doesn't work on my wife's PC.
When registering, you can specify whether it is a Mojang or a Microsoft account.
Please try both. Does it say "Download Demo Version" after logging in both times?
https://help.minecraft.net/hc/en-us/articles/360029643892-Can-only-play-Minecraft-demo-Java-Edition
We do not have any Microsoft accounts from Minecraft and the porting has not yet taken place. It is the JAVA Edition. There you only have one login.