Heskey, who is 34 in January, is in the final year of his current deal but has impressed McLeish with his performances and versatility.
McLeish, whose side visit Manchester City on Saturday, said: "Emile is in the last year of his contract but I don't think he needs to worry about his future.
"Emile is a player who can play anywhere and won't let you down. He is a fantastic professional. I never have cheek from him.
"Sometimes you'll hear coaches shout 'brilliant' from the side but the one minute you criticise them and say 'you should have done this' they're chirping back at you.
"They don't chirp back and say 'thanks for saying brilliant' of course! But Emile is a guy who gets his head down, and gets on with it.
"He is a brilliant all-round player, he understands the game, we need him in the squad."
One of Heskey's strike partners, Gabriel Agbonlahor, is winning his battle to be fit for the trip to the Etihad Stadium.
Four-goal leading scorer Agbonlahor has been suffering with a back problem this season and was substituted during the 2-0 win over Wigan a fortnight ago.
But he has looked sharp in training this week and is hoping to help Villa maintain their unbeaten start to the season in the Premier League.
McLeish said: "We are very pleased with the way Gabby has trained. Today was the most intense session for him.
"We put him through it a wee bit and he came through with flying colours.
"We expect him, barring a nightmare in training tomorrow, to be okay for the game at City."
Stephen Ireland (foot), James Collins (foot) and Barry Bannan (Achilles) are also expected to be available after the international break.
Source: Team Talk