There are two options to choose from:
FREE 3-Month Subscription to Pandora On-Demand Premium
Features: On-demand and ad-free, unlimited music, full control over music choice, search and play any song, create and share playlists, download music for offline listening, unlimited skips, and replays.
FREE 3-Month Subscription to Ad-Free Pandora Plus
Features: Unlimited skips and replays, unlimited stations, offline listening, higher-quality audio.