While "Spotify Premium" itself is a subscription service rather than a separate app, upgrading allows you to directly within the standard application. Official Methods to Download and Upgrade

: Due to Apple's billing policies, you cannot always subscribe directly in the app. Instead, use a mobile browser to visit Spotify.com/premium , log in, and select "Get Premium" to complete your purchase.

: Download the app from the Google Play Store. Once logged in, tap the "Premium" tab at the bottom right to view plans and enter payment details.