If you buy EA titles regularly you're probably used to their online pass system, a code that unlocks the online multiplayer component that you get if you buy the game new. It's a means to discourage sales of used games (that EA make no money from), and people who picks up a used game need to buy a pass online in order to play multiplayer. Somewhat surprisingly the upcoming Syndicate won't have an online pass.
There are two reasons for this, partly because games within the EA Partners programme aren't required to use an online pass, and secondly because there is no competitive multiplayer on offer. And thus in order to allow as many players as possible to play online, EA and Starbreeze agreed not to use an online pass for Syndicate.