Transitioning from free to paid, database

I have a simple database driven app. I'm looking to offer a free and paid version. The only limitation in the free version, is that you're limited to adding 10 records per month.

What is the best way to handle upgrading from free to paid, while maintaining the database?

I had planned on using in-app billing to unlock the ability to store unlimited records/month but开发者_运维技巧 I think that is probably beyond complicated for my simple app.

Other ideas were to sell an unlocker app... I don't know if people get confused by this concept though or not.

I could always write the free db to an sd card and have the paid app copy it. But a concern is people without sd cards and it just seems like something would go wrong and somebody would lose their data.

Any thoughts on this?

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If you don't want to use in-app billing then you need two separate packages, free/paid or free/unlocker. IMHO free/unlocker is far more convenient than the free/paid. In you choose free/paid you will end with two copies of the same app and you are going to have problems like the one you mention with the databases.

Android LVL is a no go in this case, you can use it to check licence and enable/disable the 10 records per month restriction, but you are limited to one package (meaning you will have the paid apk in the android market but for the "free" version you need to distrubute the application by your own).

I think PowerAMP offers a good solution. They have a free app that acts as a trial of their product and when the trial period ends, they show a dialog with a link to the unlocker app in the android market. You can use the same strategy, when a user tries to enter more than 10 records/month show them an alert with a link to the unlocker app. I think this should solve your concern about people getting confused.