During the service, which was held at Elvis' Graceland home in Memphis, Tennessee, Riley, 33, remembered her mother's enduring love and strength in a speech delivered by her husband, Ben Smith-Petersen.
"I'm eternally grateful to have spent 33 years with you. I'm certain I chose the best mother for me in this world... I remember everything. I remember you giving me baths as a baby. I remember the way you would cuddle me ... and the way you smelled," said Smith-Petersen onstage as his wife sat front row with her family, including Priscilla Presley.
John Sciulli/WireImage Riley Keough and Lisa Marie Presley in 2012
"I remember all the notes you'd leave in my lunchbox every day. I remember the feeling I'd get when I'd see you picking me up from school ... I remember how it felt to be loved by the most loving mother I've ever known. Thank you for showing me love is the only thing that matters in this life. I hope I can love my daughter the way you loved me, the way you loved my brother and my sisters," he continued, revealing he and Keough welcomed a baby together. "Thank you for giving me strength, my heart, my empathy, my courage, my sense of humor, my manners, my temper, my wildness, my tenacity. I'm a product of your heart.
"I hope you finally know how loved you were here. Thank you for trying so hard for us," he concluded. "If I didn't tell you every day, thank you."
On Friday, Keough shared a throwback black-and-white photo on Instagram of herself with Lisa Marie.
The actress left a simple message to go along with the photo in her first public statement since her mother, the only child of rock legend Elvis Presley and Priscilla, died: "❤️."
Lisa Marie died Jan. 12 at age 54 after being rushed to a Los Angeles hospital for a possible cardiac arrest.
The singer-songwriter is survived by her mother, actress and businesswoman Priscilla, 77; and her three daughters, Riley and twins Finley and Harper Lockwood, 14, and her granddaughter. Lisa Marie was preceded in death by her son Benjamin Keough, who died by suicide at age 27 in 2020.
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In December, Riley — whose father is Lisa Marie's first husband Danny Keough — spoke to PEOPLE about her upcoming show Daisy Jones & The Six — and said that her mom embodied the character in the show.
"My mother is certainly an inspiration to me," said Keough, adding that Lisa Marie was "a very strong, smart woman."
She continued, "I was raised by somebody who did their own thing and didn't really care what other people thought. She was definitely inspirational to me."