Metallica never plays the same show twice.

The American heavy-metal rock band, whose debut album was released 35 years ago this week, caters its live performances to its fans.

It looks at what audiences are listening to on Spotify in the city it’s playing in, and changes the setlist to include some of the most popular songs in that area, Daniel Ek, Spotify’s CEO, said on his company’s earnings call today.

“You have an artist like Metallica, who changes their setlist on a city-by-city basis just by looking at Spotify data to see, which the most popular songs happened to be in that city,” Ek said. “We’ve never before been at a place in time where you could make as many informed decisions and understand your audience as well as we can do now as an artist.”

A firm that represents Metallica did not immediately return Quartz’s request for confirmation.

Artists and labels know more than ever about who their fans are, in part, because of the listening data Spotify gathers and shares with them, Ek said. It’s one of the ways he says his company is helping to change the music industry.

Live shows are an increasingly important way for artists to make money, in part because subscription services like Spotify have weakened sales of albums and music downloads. Metallica records each of its live shows and fans can buy the audio files on livemetallica.com, which makes it even more crucial that each show is unique.

The band has been thoughtful—some might say, obsessive—about constructing its setlists since before Spotify launched in 2008. Each time the band returns to a city, drummer Lars Ulrich analyzes the last decade or so worth of performances in that area. He changes six to eight of the songs in the setlist to give audiences a different experience, Ulrich told radio station 97.9 Baltimore in 2017. He also looks at the songs that are playing on the radio in that area.

Ulrich has been doing that since around 2003, and the band hasn’t repeated a setlist since. Insights from Spotify would certainly help to that end.

“Obviously there’s certain songs we have to play,” Ulrich said, “but then there’s the deeper cuts, and the deeper cuts I always try to vary…I don’t play the same setlist twice and I try to play different songs for whatever city we’re in depending on what we played the last time.”

Fans may recall that Metallica took a hardline against file-sharing site Napster, which was commonly used to illegally download music, suing the company in 2000. The band later embraced digital music, releasing its catalog on Spotify in 2012.