A repost of Half-Life 2 and CSS help

Due to my stupidity I posted this in the wrong forum, and i’m not sure if I should be posting it again but would it be considered illegal to put the CSS materials and HL2 materials into my gmod addons directory? I bought HL2 at a market and the code was already used.

And on another note, would it be considered illegal to copy other game files into my addons directory if I bought the games on a different account?( Ill be them on this account soon enough though)