Pandora Radio no longer working

I installed Pandora Radio on Friday. The application worked great until last night. I received streaming music early in the evening, turned off the phone. Later I turned the phone back on and Pandora did not work, it still doesn't work this morning.

The application comes up when selected. I received the grey screen that states Pandora, but after 2-3 seconds the application closes. I used to get the loading circle but don't get that either. I am not sure what changed. Is Pandora a service that I need to pay for? I am still able to get into itunes and app store.

Let me know.

Thanks