Elliot lived in a swanky apartment in San DiFrangeles during her intern year and first year as a resident because she was still living off an allowance from her father. When she stood her ground and refused to enter the OB-GYN field, she was cut off financially and had to move out. ("My Fruit Cups")
She was temporarily homeless and tried to live in the break room and her moving van before J.D. offered his couch to crash on. ("My Monster") Once she moved in, they relapsed into their sexual attraction and spent the night together. After trying to be "sex buddies", they realized they couldn't be a couple because it didn't work the last time. Elliot decided to find a new apartment so she wouldn't need to crash at his apartment anymore. ("My Sex Buddy")
Elliot found another place to live, but her moving van was stolen so her had to start furnishing her apartment from scratch. ("My New Old Friend") Her new place turned out to work fine, and after entering private practice, she made enough money for it to be a really nice flat. ("My Friend with Money").
Over the years Elliot has had several people stay at her apartment. After being kicked out of his apartment by Turk and Carla, J.D. moved in while looking for a place of his own. ("My Big Move") Keith had his own place, but due to their relationship and engagement, he was often at Elliot's apartment. This made things awkward for J.D. when he crashed there.