Molly Ringwald, who portrays Perry's on-screen wife, Mary Andrews, described the episode as "cathartic", as she was not able to attend Perry's memorial, and it allowed her to say good-bye to him. KJ Apa, who plays Perry's on-screen son Archie, recalled it being "a tough one because you have to kind of go back in time a little bit and go back and access that emotion again." In the United States, the episode received a 0.4/2 percent share among adults between the ages of 18 and 49, meaning that it was seen by 0.4 percent of all households, and 2 percent of all of those watching television at the time of the broadcast. It was watched by 1.14 million viewers. At the time of airing, the episode garnered the highest ratings since the season three episode, "Chapter Forty-Six: The Red Dahlia", which garnered 1.26 million viewers. On review aggregator website Rotten Tomatoes, the film holds an approval rating of 100% based on 14 reviews, and an average rating of 9.47/10. The site's critics consensus reads: "Bittersweet and beautiful, "In Memoriam" is a loving tribute to the beloved Luke Perry -- a fitting sendoff for one of TVs favorite dads." The episode received unanimous acclaim, with critics praising how the show handled Perry's death. Alexis Nedd from "Mashable" praised "the level of care that went into crafting the season premiere." She acknowledged the difficulty in watching some of the scenes because the emotions portrayed on screen mirrored those of the cast. Molly Fitzpatrick of "Vulture" and Samantha Highfill of "Entertainment Weekly" both gave positive reviews, calling the episode a fitting and beautiful tribute   Charles Bramesco of "The A.V. Club" gave the episode an A-, praising the show for its handling of the topic, complimenting the "foundation of earnest emotion in the response of the viewers at home, and the same goes for the performances from the actors who've parted with one of their own", singling out KJ Apa's performance in particular. In his review for "Decider", Alex Zalben praised the episode for "it's decision to put the viewer in Archie's shoes" by showing him grappling with his father's death. Laura Bradley of "Vanity Fair" praised the way the show handled the plot, focusing more on the emotions of the characters. In her review for "The Washington Post", Sonia Rao praised how "Riverdale" "shed its campy neo-noir skin" to honor Perry and his character, and "instead [adopted] a more earnest tone to highlight the qualities that defined Fred."