The 27-year-old was publicly deemed surplus to requirements by Emery last month but failed to secure a move away from Emirates Stadium.
Emery said: “When he decided [to stay] I spoke to him and said 'you're one more in the squad, I'm going to work with you as other players'.
“He decided to be here, I don't know exactly who was in his decision but when we spoke and he decided to stay here it's a start with him as another player in the squad.
“Really, since he decided to stay here, he's working every day with a big motivation and good spirit.
"That is one issue I want from every player: training with good spirit, helping and after giving us his performance in training and the match."