From a cursory Google search, it looks like quite a bit of the passwords to those premium accounts were "simple" enough to brute force/try out, like "iloveyou"…
Spotify accounts breached
Spotify account-holders' details have appeared on Pastebin. User names, passwords and email addresses are among the details divulged. Spotify says it has not been breached, leaving open the possibility that users had entered their account details into a third party or phishing service. The company is informing affected …