Spotify Premium [FREE]

1. Go to Settings > General > Profiles or Profiles & Device Management.
2. Under the "Enterprise App" heading, you see a profile for the developer.
3. Tap the name of the developer profile under the Enterprise App heading to establish trust for this developer.
4. Install Spotify++.
5. Log in your account.
6. In the search bar, search for no copyright sound.

This method does not allow you to download for offline.