The striker joined Everton last summer after Jose Mourinho afforded the Belgian a second temporary switch following a 17-goal return for West Brom the previous season.
|5/1||Everton are 5/1 with William Hill to finish in the top four next season|
"In any loan deal you do, all you want is for it to be a real success," he told reporters. "I'm really pleased to say now that Romelu Lukaku has been a real success.
"I've seen him grow as a player, as a man and as a footballer and I think he has developed unique memories with Everton.
"I think you saw it today that the fans will always have great memories of Rom's footballing talent.
"Chelsea will be delighted with the progress of the player and we have benefited from having a player like Rom.
"Whatever happens next [for Lukaku] will always be positive and a part of what happens in the future."