Android developers are presented with a number of ways to monetize their content on the Google Play store. One of the more prominent methods is through the use of subscriptions. In essence, a player pays a monthly fee for a set amount of microtransaction content. Now developers can hook potential subscribers with free stuff.
Google recently added a new section to the billing subscription guide that details how developers can offer free trials for their subscriptions. The free trial offer is extremely open ended and allows developers to offer seven days or more of free subscription goodness.
For users, initiating the free trial will require them to "purchase" the full subscription through the in-app purchasing system. This means that users must have a valid form of payment as their card starts getting billed as soon as the free trial ends. The user will not be charged whatsoever though, and the transaction will appear as $0.00 on a developer's transaction records.
Interestingly enough, canceling the free trial is handled a bit differently from canceling a subscription. Ordinarily, the subscription benefits would continue throughout the period even if the user canceled the subscription at the beginning of their subscription period. Canceling the free trial will end all benefits immediately.
Developers who already offer subscriptions have nothing to lose from adding free trials. Implementing the free trial only takes a quick edit of the subscription in your product list. Free trials must be set for a minimum of seven days, but can be as long as you want after that. Developers can also only create one free trial period per subscription product.