There is no cost to listen to the feeds.
In the future (a long way away from now), if you're listening using a web browser and you are not a Broadcastify Premium Subscriber you'll be limited to 2 hours of continuous listening time (when using the Web Player or Java Web Player to listen). After you've listened for 2 hours you'll need to reload the web page containing the player to continue listening.
Broadcastify Premium Subscribers will have unlimited continuous listening regardless of what player they use.
Listening using all other players (WinAmp, iTunes, VLC, mobile, etc) will remain unlimited (no time limits).