Under the terms of the deal, Bertelsmann will integrate Napster's Web infrastructure - except for peer-to-peer file sharing - into its BeMusic division.
BeMusic includes the conglomerate's music and entertainment properties including online-music retailer CDNOW, record clubs, and the digital-music-locker service myplay, which Bertelsmann agreed to acquire in May.
Web set-up "Each of these companies has its separate Web presence and IT architecture," said Bertelsmann spokesman Alexander Adler. He added: "But we've found the Napster-community features, such as hot lists and chat features, very convincing."
By standardizing its various offerings on Napster's architecture, Bertelsmann hopes to offer a "one-stop shop", Adler said, so that, for example, a customer could buy a CD from CDNOW and have the contents automatically uploaded to a myplay online music locker.
However, the peer-to-peer file sharing that made Napster hugely popular with music fans is not part of Bertelsmann's plan.
"That will remain with Napster," Adler said. He declined to say when Napster might offer its long-awaited, fee-based business model.
Bertelsmann has increasingly been involved in Napster since extending a loan to the lawsuit-battered company last year. The new deal "shows how confident we are in the Napster IT infrastructure, and how much trust we have", said Adler. He claimed: "It's a clear signal that Bertelsmann and Napster will continue to work together."