Open episodes allow everyone to explore the content of episode 1-26 without any purchases, although the most recent Episode 27 will remain locked off to non-members. Players who already have access to the content (either by purchase or membership) will have shorter loot timers, so even if you’re an old hand at the game you’re still gaining something on the exchange. So go on, enjoy some story content no matter how experienced you are with the game; you’ve got until December 31st to get in on the open festivities.
DC Universe Online who hasn’t yet decided to subscribe. Maybe you’re a former subscriber who wants to wrap up storylines but isn’t sure if it’s worth the time. Maybe you fall into neither category, but you still want to go play through the game’s episodic updates. The good news is that you totally can play through the game’s episode stories without buying anything through the end of the year.
Source: Official Site