You are mixing different things into each other. Steam is a software/store to purchase (not sure if purchase is the correct term) video games. Steam requires y

You are mixing different things into each other. Steam is a software/store to purchase (not sure if purchase is the correct term) video games. Steam requires you to use an account and all your purchases are logged in it. So when/where-ever you use that account, you have access to the games. Steam forces you to authenticate online with your account before you can use the Steam software to run the games. If you fail to authenticate or if Steam decides to remove your account or else, you cannot use Steam. That is the DRM part.