TOR Quick Question About Events

I'm returning to the game after a long absence. Since launch I've been on and off of playing, and as a result I've missed lots of the event stuff. I plan on paying the sub fee when I return, but I wanted to know in advance if it's possible to experience all the events and etc. after they've ended? Do they rotate the different ones, keep them in the game world, or once they're done, they're done?

Thanks!