The Allman Brothers Band played its first set on Tuesday night at the Beacon Theater sounding relaxed and steady, on midboil, with some fairly long pauses between songs: “One Way Out,” “Good Morning Little Schoolgirl,” “Midnight Rider” and so on.

The recognizable details of an Allman Brothers set were there: shuffles, fast and slow blues, harmonized guitar melodies, and sequential solos by Warren Haynes and Derek Trucks. Transitional arrangements were carpentered into the music, and improvised drum passages came in triplicate from Jaimoe, Butch Trucks (Derek’s uncle) and Marc Quiñones. But the mood registered somewhere between steady and spooky: the sound of a band under pressure but peaceful, almost as if it were playing for itself.

Tuesday’s concert was, as far as anyone can see, the Allman Brothers’ last. It was billed that way in advance and confirmed as such by the band’s leader, Gregg Allman, last week, before the first of their six Beacon shows. Of course, they could form again for an awards show or a benefit, or something, somewhere. Still, it looks reasonably final.

Statistics: The band has been running for 45 years, and in this version for 15, with Mr. Trucks and Mr. Haynes. It has played an engagement nearly every year since 1989 at the Beacon Theater — more than 230 concerts. Both its guitarists announced in January that they intended to leave the group by the end of this year.