Years from now, we’ll look back on One Direction’s third release, “Midnight Memories,” as the band’s last album before everything was ruined.

Everybody knows that One Direction is simply the latest bunch of boys in a long line of boys — young men with no pedigree, lots of charm and just enough talent, a lineage that stretches back to the Monkees. These boys began as contestants on the British version of “The X Factor” (finishing in third place) instead of being forged in Lou Pearlman’s Orlando Finishing School in the manner of obvious ancestors Backstreet Boys and ’N Sync. But once it starts, it always goes the same way: The first album (“Up All Night,” 2011) is the out-of-nowhere breakthrough. The second album (“Take Me Home,” 2012) is a careful re-staging of the first album, which solidifies the band’s reign. The third album is the one where the group asserts its independence from handlers, professes a greater interest in writing its own songs and experiments with PG-13 subject material and a more mature sound.

Everything usually starts falling apart after that.

“Midnight Memories” faithfully executes its third-album duties. One Direction members are credited with co-writing nearly every track, the songs are expertly made, impressively (sometimes very impressively) sung, nominally more adult and in every way quite decent, which is all they need to be.

The ratio of good songs to inoffensive filler is refreshingly high, though 1D has yet to place a song on Boy Band Mount Rushmore alongside “I Want It That Way” and “End of the Road.” These boys have never made a great song, which is the sort of thing that should worry pop-culture historians.

They’re also little more than a cuteness delivery system with interchangeable parts, which is the sort of thing that should worry the band. Despite years of exposure, the members’ individual personalities aren’t as fully fixed (at least in American minds) as they might be. There’s the one who had a halfhearted romance with Taylor Swift . . . and the other ones. So many things we don’t know: Who might be the first to unwisely go solo? To be hospitalized for “exhaustion”? Which one is the Justin Timberlake?

Like any mega-album aimed at tweens, “Midnight Memories” must exist on several levels. On the surface, it’s a conventionally catchy pop album about love lost and found, about never giving up because your heart can love again. Underneath, there are coded lyrics aimed squarely at the legions of young Directioners that serve as reassurance that the boys are still the same approachable moppets they always were: Don’t worry, we’re still saving it for you. The older the fan, the broader the definition of “it,” but “Midnight Memories” has that covered. With the help of a lot of double and triple entendres, “Midnight Madness” is one album to the ears of innocents and another album to everybody else.

“Diana” is a masterful piece of popcraft that offers up the most validating couplet in boy band history: “You don’t even know me / But I can feel you crying.” “Best Song Ever,” equally superb, is about a girl who walked “through the doors and past the guards” and left with the heart of a figurative prince/band member. For everyone born before 2000, there’s the raucous but otherwise forgettable “Happily” and the bonus track “Why Don’t We Go There,” in which a girl is convinced to part with her boyfriend (“I wonder if he knows that I touched your skin / And if he feels my traces in your hair”) and her virginity (“We’ll touch the other side / Just give me the key”), respectively.

It may not sound like much, but it’s the middle-school equivalent of “Fifty Shades of Grey” and a necessary part of One Direction’s snail’s-pace evolution from young and innocent to slightly less young and innocent. The boys have also beefed up the pop-rock elements that have always been crucial to their sound. In theory, it’s a wise move — boy bands too often equate adult-contemporary pop-and-b with maturity and wind up sounding like old fogeys on the reunion tour. (Which will happen when they’re 32.)

The problem is that One Direction simply isn’t as good at rock-and-roll as it is at everything else. Tracks such as the glam-inspired “Little Black Dress” and the pep-rally-rocking title track don’t play to the band’s strengths, nor does the sheer volume of draggy, boneless ballads.

The only time the boys really sound like themselves, when they don’t sound like they’re imitating the Lumineers or Ed Sheeran or Coldplay, is on the pure pop songs. That “Best Song Ever,” with its cascading harmonies, could easily have been a Backstreet Boys song speaks to the universality of the greatest boy band pop, and also to its fleeting glories. The best One Direction songs are precisely the sort of songs they’ll soon be too old for.

Stewart is a freelance writer.