
This offer is part of the "12 Days of Play" promotion program, although not available to everyone. Google has not released an official statement regarding qualified users who can enjoy the promotion.
A number of Google Play Music subscribers claim to have enjoyed trial bids and get four months to enjoy music, though not new customers.
Additionally, the offer does not appear in all subscribers, and the availability of a four-month free trial offer for customers is only known by visiting the official Google site promotion page.