Free trial for one-time purchases?

[jmartingit]

In my app, I offer three billing options when upgrading to premium:

• A monthly subscription (with 7-day free trial).
• A yearly subscription (with 7-day free trial).
• A one-time purchase for those who don't like subscriptions (no free trial).

(Many apps are following this hybrid model lately).

Since the billing library doesn't provide a way to implement free trials on one-time purchases, users who want to try the app before committing are forced to (1) start a free trial with a subscription option, (2) cancel the subscription before the trial expires, (3) buy the one-time purchase after the trial expires.

This causes a lot of friction and there are too many points where the purchase may be lost.

It would be great if the billing library provided a way to implement free trials with one-time purchases. Is that a possibility? Is there a different way to implement this?