Marketplace
This offer is for new subscribers only.
After your 90-Days, your subscription will automatically renew at a rate of $9.99 per month, however you may change or cancel at any time. This subscription includes unlimited streaming access to music from the Google Play catalogue, playback on multiple devices, and curated radio stations
They recently had this for free, but good deal nonetheless.
You may also find a 90 trial is being offered to Chromecast customers, but I'd need to check if is still available.