The Gunners’ captain bagged a brace in Sunday’s 3-2 win over Everton at the Emirates to take his season’s goals tally to 17 in the Premier League.
Aubameyang raced clear of the Toffees’ defence to put Arsenal 2-1 ahead, before heading them in front again after Richarlison had levelled.
His second goal straight after half-time proved to be the all-important winner, and pundit Souness feels his value to Arsenal cannot be understated.
“He is 30, he is at the top of his game.” Souness told Sky Sports. “He is a really good player.
“Coming here I was worried how he would deal with the English game but he has taken it all in his stride.
“You see two different goals today, one where he has got a chance of getting properly injured with a coming together of heads, but he didn’t pull out in any shape. Good header, stuck it away.
“The one before that when he is set free, and very Thierry-esque where he is free. The alarm bells are ringing for a lot of strikers in that position, but when he gets free you’re thinking he is gonna put this away.
“He didn’t get excited and stroked it and passed the ball into the net.
“He is a top man. Can they hold onto him? It is imperative they do.”
Aubameyang’s Arsenal contract is running down, with just over a year remaining on his current deal.
Boss Mikel Arteta made it clear Aubameyang is a key feature of his plans for Arsenal going forward, and is keen to tie the forward down to a new contract.
“He’s a superb player,” Arteta said after the match. “He completely deserves to be liked by other teams but hopefully we can convince him that this is the right place for him. And he has a future here.”