I checked the Pandora account associated with your community profile and I do see that it is upgraded to a 30-day trial of Pandora Premium through Google Play.
I've confirmed that your subscription on this account has been canceled. You will not be charged when your trial expires.
You can view your expiration date from your Android device:
Launch the Google Play Store app.
Tap the menu icon at the top left of the screen (3 horizontal lines), then Subscriptions.
Then find Pandora under Subscriptions.
If you're not able to see this subscription through your Google Play account, it sounds like you may have more than one Google Play profile, or another Google Play account under an alternate email address.
Unfortunately, I have limited access to the Google Play billing system and I'm not able to search for any other Google Play accounts.