Did Harry Potter get expelled in the last book?

Answer 1

Harry Potter was not expelled he was almost expelled because he performed magic outside of school - for the second time - and in front of a muggle. However he was cleared of all charges because there was a witness to the dementors.

He also nearly got expelled because of Dumbledore's Army. However due to the name Dumbledore took the blame so that Harry was not expelled. But then Dumbledore had to escape.

Note: In the second book Harry was blamed for a spell which Dobby the house-elf performed.

Answer 2

No, he quit because Snape was Headmaster of Hogwarts

He didn't quit because Snape became Headmaster, he chose not to go back so as to find and destroy the remaining Horcruxes in order to kill Voldemort. He found out that Snape was Headmaster after this decision (actually made at the end of the 6th book).

Answer 3

He was nearly expelled every year except his sixth (and seventh since he never attended). His closest call to being expelled was in his fifth year; Harry Potter and the Order of the Phoenixwhen he was summoned to a hearing about using magic outside of school.

Answer 4

The Order of the Phoenix, for performing underage magic.

Answer 5

Harry Potter and the Order of the Phoenix - book five.