Time trial for one-time purchases with Google Play In-App Billing

Question

Currently, I have a free to download app with limited features. In order to unlock full features, user will need to go through one-time purchase, with Google Play In-App Billing.

Recently, to increase conversion rate, I plan to offer time-trial full features.

That's mean, user able to use the full features for first 7 days, without having to perform one-time purchase.

After 7 days, he will fall back to app with limited features. If he likes the full features in the last 7 days, he will perform one-time purchase. If not, he will just let it be :)

I was wondering, is there any way I can utilize existing in-app purchase billing API, to achieve my time-trial feature?

I prefer not to handle server side by my own, if that's possible.

I know in-app subscription model does offer trial period : http://developer.android.com/google/play/billing/billing_subscriptions.html

However, subscription model is not what I'm looking for. Mine belongs to Non-consumable Items

Answer 1

Google's in-app billing will not directly support your case of a trial. This is because the in-app billing is a simple one-time purchase model (for managed in-app products), which simply handles the actual purchase flow and ownership management. It's up to you to provision the actual in-app product based on the purchase and ownership provided by Google.

So this means that you'll have to implement:

1) Your trial of the full-features for 7 days, entirely within your own code. Specifically you'll have to figure out how you are going to implement this in such a way that a user cannot simply uninstall and reinstall the app to get a fresh 7 days.

2) Once the user trial has elapsed, your app will have to lock the full features.

3) Your app should then support a purchase flow through Google in-app that, when completed, permanently unlocks the full features.

Obviously the tricky part of this is (1). This will likely require some server-side tracking on your end of device and/or user IDs, as any solution which is reliant solely on client-side storage could easily be exploited for multiple trials.