Former players who are no longer subscribed can log in at any convenient point, and the account will be flagged for logging back in for up to five days. That means five days to explore what’s new in the game and decide if it’s what you had been waitin to have in the game when you stepped away at first. There’s also a new crossover event coming out tomorrow, so there’s even more stuff to do in the very near future.
Source: Official Site