The free trial lets you use Solitaire Premium for one week at no cost. At the end of the week, it will renew at the normal monthly subscription price of $X USD, or equal to the same price tier that “Google’s App Store Matrix” determines in other currencies, charged every month to your Account.

If you are unhappy, you can end your subscription by turning off automatic renewal in the Play Store app. To avoid the first renewal charge, you must turn off automatic renewal at least 24 hours before the free trial period ends. See How do I stop or change my subscription below.