Don't really know the typical format of these threads so

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Don't really know the typical format of these threads so I'll try my best. Not going to greentext either sorry.
One of my housemates (pretty wealthy, always buying stuff like tv's and random stuff from Amazon) is an extremely forgetful and messy person. He's mostly moved out of our house, almost never here.
Months and months ago he gave me his 3ds to hold on to (not keep).
I'm almost certain he has forgotten about this.
I'm considerably less wealthy than this guy, and he doesn't play the 3ds anyway.
That being said, I don't hate him. He's the type of guy to cheat on his girl and make passes at his friends girlfriends, but I don't know if taking from him is right.
What is the moral conflict here? If I don't remind him that his 3ds is in my possession when we move out next month is that shady of me?
What would others do in situation?