In an Instagram post, Lourd, 27, and a few friends sing an acoustic version of "American Girl" by Tom Petty in her mother's honor.
"Happy birthday, Momby," she captioned the video. "Today would have been my Momby's 63rd birthday. Not that I'm some kind of grief expert by any means, but on milestones (or whatever you want to call them) like this, I like to celebrate her by doing things that she loved to do."
Lorde then explained her choice in song and setting.
"So here's a little video of me singing one of her favorite songs (American girl by Tom Petty) in one of her favorite places (her bathtub of course). I'll probably have a pint of vanilla Haggen Dazs and a Coca Cola for dinner."
Lourd received praise from friends like her "Scream Queens" co-star Keke Palmer, saying "I love you Billie!" and Cheyanne Jackson, who commented "just perfectly beautiful. Like you, honey."
Fisher's "Star Wars" co-star Mark Hamill also commented. "#AlwaysWithUs," he said.
Lourd also posted a video of herself singing in December of last year, saying "It's been 2 years since my Momby’s death and I still don’t know what the 'right' thing to do on a death anniversary is... So I decided to do something a little vulnerable for me, but something we both loved to do together - sing. This is the piano her father gave her and this was one of her favorite songs. And as the song says, we must “keep on moving.”
In the video, she sang "These Days" by Jackson Browne.
Fisher died unexpectedly in December of 2016 after a heart attack on an airplane. Fisher's mother and Lourd's grandmother, Debbie Reynolds, died just a day later after a stroke at the age of 84.
Lourd is currently starring in the ninth season of "American Horror Story," and will be seen in "Star Wars: Episode IX - The Rise of Skywalker," which will use archive footage of her mother as well.