The forward netted twice at Craven Cottage as the Gunners picked up a 3-1 victory to get off the mark for the new season.
"I am pleased for him because he hasn't started much recently more because of the balance of the team than his performances," Wenger told the club's official website. "I am pleased because he plays with a lot of spirit and he can score goals. Everybody in the squad loves Lukas and I want to keep him."
Arsenal host Fenerbahce in the second leg of their Champions League playoff on Tuesday after beating the Turks 3-0 in midweek.