A spokesperson for the firm told TechRadar that there is no future in freemium streaming because the business model is not sustainable.
"In terms of Spotify, there is no evidence that their 'freemium' business model is sustainable, as their numbers for the last two years show," said Napster in a statement.
Napster, which has around three million premium customers, also took a thinly-veiled pop at Apple Music and its Zane Lowe-curated Beats 1 Radio service.