The 30-year-old was in the final year of his contract at the Stade Gerland and opted to call time on a four-year spell, that yielded 81 goals in 167 matches, with a move to Qatar.
And Garde was quick to praise Lopez after watching his side run out 4-0 winners over Nice on Saturday, as well as singling out his namesake, Anthony, and the two goal efforts of Alexandre Lacazette.
"I'm happy for Alex Lacazette. I also wanted to make a huge tribute to Licha (Lopez). I will not forget what he did," Garde told reporters after the game.
"I am pleased that we did not concede any goals tonight," Garde added.
"That is the third game we have played in a row without conceding. Like in the other times, we can thank Anthony Lopes who saved us in goal.
"Lopes had to make some good saves and the fact we did not take any goals was important for the confidence of the players.
Clement Grenier and Yoann Gourcuff scored the game's other two goals as Lyon look to build on last season's third-place finish in Ligue 1.