Instead, due to production difficulties, it was shelved for nearly three decades, until it was completed by his surviving bandmates Paul McCartney and Ringo Starr, using overdubs and guitar tracks by George Harrison (who died in 2001) from the abandoned 1995 sessions.

[5] Lennon's voice was extracted from the demo using the machine-learning-assisted audio restoration technology commissioned by Peter Jackson for his 2021 documentary The Beatles: Get Back.

[15] Writing for the Los Angeles Times, Stephen Thomas Erlewine called Lennon's song "a wispy, melancholy ballad".

[5] Referring to the original demo, Craig Jenkins of Vulture said "'Now and Then' languished in an unfinished state, its vocal and piano melodies enshrouded in too dense a thicket of abrasively scratchy hiss to massage into the high-quality recordings the Beatles were known for".

[16] In January 1994, the year Lennon was posthumously inducted into the Rock and Roll Hall of Fame,[17][2] his widow, Yoko Ono, gave Paul McCartney two cassette tapes she had previously mentioned to George Harrison.

[21] During a Lynne documentary shown on BBC Four in 2012, McCartney stated about the song: "And there was another one that we started working on, but George went off it... that one's still lingering around, so I'm going to nick in with Jeff and do it.

[23] For the 2021 documentary series The Beatles: Get Back, director Peter Jackson's production company WingNut Films isolated instruments, vocals, and individual conversations utilising its audio restoration technology over a four-year period.

WingNut applied the same technique to Lennon's home recording of "Now and Then", while preserving the clarity of his vocal performance separated from the piano.

[32] McCartney recorded bass guitar, a slide guitar solo in the style of Harrison as a tribute to him, electric harpsichord, backing vocals, and piano in the style of Lennon's demo in his home studio in East Sussex while Starr later recorded a finalized drum track and backing vocals in his home studio in Los Angeles.

Ben Lindbergh of The Ringer contrasted the original recording to the released version: "McCartney collaborates with his former muse not just by building on Lennon's work, but by undoing it.

The Beatles release is almost a minute shorter than the Lennon demo, largely because the latter includes two pre-chorus bridges that the former removes (aside from a subtle, hard-to-hear allusion in McCartney's piano chords during the new solo)".

"[34] The finished track was produced by McCartney and Martin, while Lynne was credited for "additional production", and mixed by Spike Stent.

[35] On 13 June 2023, McCartney told BBC Radio 4's Today programme that he had "just finished" work on extracting Lennon's voice from an old demo of the latter's in order to complete the song, using (in his words) artificial intelligence.

[37] The design of the back cover art for the vinyl single incorporates a photograph of a handmade, folk art clock made from recycled materials by artist Chris Giffin which had been purchased by George Harrison in Providence, Rhode Island during a 1997 trip to visit his son Dhani who was attending Brown University.

According to Olivia Harrison, George's widow, in the summer of 2022, after having recently cleaned the clock and replaced its battery, Paul McCartney called her to discuss plans for the release of the new Beatles single "Now And Then".

[42] The short film tells the story of the song's inception, including commentaries by McCartney, Starr, Harrison, Sean Lennon, and Jackson.

[7] To celebrate the release of "Now and Then", animated projection mappings of the cassette tape from the Beatles' website popped up at Beatles-related locations across Liverpool, including the Strawberry Field, the road sign for Penny Lane, outside Lennon's childhood home, and the Cavern Club.

[30] In an interview days before the song's release, Jackson claimed that he had originally been "very reluctant" due to the heavy responsibility of directing the video, stating: "I knew The Beatles don’t take no for an answer if their minds are set on something - but they didn’t even wait for me to say no.

[49] In the first review published for its completed incarnation, Erlewine wrote in the Los Angeles Times that the track was "elegant [and] softly psychedelic" with "a wistful undercurrent", calling it "a fitting conclusion to the Beatles' recorded career – not so much a summation [but rather] a coda that conveys a sense of what the band both achieved and lost".

[51] Ed Power of The Irish Times praised Lennon's vocals on the track, deeming it "a 2023 pop odyssey sure to warm the cockles of Beatles fans young, old and in-between".

[52] Vulture's Craig Jenkins said the tune had lyrics and orchestral flourishes similar to "The Long and Winding Road", writing "If this is the end of the Beatles, they have left us with a snapshot of their strengths.

"[54] Mark Beaumont of The Independent gave the tune a perfect five-star rating, writing "Sorry Swifties, hard luck Elton, in your face Sphere – this is the musical event of the year and one of the greatest tear-jerkers in history.

[66] Peter Jackson's music video was met with polarized reviews, with praise for its emotional weight but criticism regarding the insertion of Harrison and Lennon into more recent footage.

In a mixed review, Mark Woods of the Beatles-themed website Zap stated: "I have read the Peter Jackson interviews, heard his approach to it and knew that not only did he have the Anthology session footage but also an unseen clip courtesy of Pete Best, and my mind had put together a chronological journey through Beatledom.

Pepper-era Lennon and Harrison is jarring and frankly, a little goofy [...] Nevertheless, Beatle fanatics may find themselves charmed by the time capsule quality of the video, which travels backward through the group’s career all the way through to childhood photos and footage of the four members.

"[68] In a positive review, Purav Menon of The Oxford Student stated: "Though [the inserted Harrison and Lennon] can border a little on the uncanny valley side, the video is an emotional experience, particularly the final third, which takes the Beatles all the way back in time to their beginnings as the Quarrymen in the Cavern Club in Liverpool.

The song finishes with the Beatles bowing following a live concert, and then disappearing from the frame, a creative decision from Jackson that almost brought a tear to my eye (even as someone who wasn’t old enough to experience half of the band being alive, yet alone performing and releasing music!).

"[69] Conversely, Sam Adams of Slate called it "an abomination" that "shows that Peter Jackson has really, truly lost it" and that he "wants to do more than collapse the decades; he wants to erase them.

[74] In the United States, it debuted at number one on the Billboard Digital Song Sales chart for the week ending 11 November 2023.

[75] "Now and Then" debuted at number 7 on the Billboard Hot 100 dated 18 November, and was their 35th top ten single on that chart with 73,000 units sold.