Creating an Android trial application that expires

Question

I have an application which I want to hit the market as a Paid app. I would like to have other version which would be a "trial" version with a time limit of say, 5 days?

How can I go about doing this?

Answer 1

Now in the recent version of android free trial subscription has been added, you can unlock all your app's features only after buying the subscription within app for a free trial period. This will let the user to use your app for a trial period , if the app is still uninstalled after the trial period then the subscription money will be transferred to you. I have not tried , but just sharing an idea.

Here's documentation

Answer 2

@snctln option 3 can be easily done adding a php file to a web server with php and mysql installed as many of them have.

From the Android side an identifier (the device ID, google account o whatever you want) is passed as argument in the URL using HttpURLConnection and the php returns the date of the first install if it exist in the table or it inserts a new row and it return the current date.

It works fine for me.

If I have time I will post some code !

Good Luck !

Answer 3

Hey guys this question and the answer of snctln inspired me to work on a solution based on method 3 as my bachelor thesis. I know the current status is not for productive usage but I would love to hear what you think about it! Would you use such a system? Would you like to see it as a cloud service (not having trouble with configuring a server)? Concerned about security issues or stability reasons? A soon as I finished the bachelor procedure I want to continue working on the software. So now its the time I need your feedback!

Sourcecode is hosted on GitHub https://github.com/MaChristmann/mobile-trial

Some information about the system: - The system has three parts, a Android library, a node.js server and a configurator for managing multiple trial apps and publisher/developer accounts.

• It only supports time-based trials and it uses your (play store or other) account rather than a phone ID.

• For Android library it is based on the Google Play licensing verification library. I modified it to connect to the node.js server and additionally the library tries to recognize if a user changed the system date. It also caches a retrieved trial-license in AES encrypted Shared Preferences. You can configure the valid time of the cache with the configurator. If a user "clear data" the library will force a server-side check.

• Server is using https and also digital signing the license-check response. It has also an API for CRUD trial apps and users (publisher and developer). Similiar to Licensing Verfication Library developers can test their behaviour implementation in the trial app with test result. So you in the configurator you can explicit set your license response to "licensed", "not licensed" or "server error".

• If you update your app with an ass-kicking new feature you might want that everyone can try it again. In the configurator you can renew the trial license for users with expired licenses by setting a versioncode that should trigger this. For example user is running your app on versioncode 3 und you want him to try features of versioncode 4. If he updates the app or reinstall it he is able to use full trial period again because the server knows on which version he has tried it last time.

• Everything is under the Apache 2.0 license

Answer 4

Approach 4: use the application install time.

Since API level 9 (Android 2.3.2, 2.3.1, Android 2.3, GINGERBREAD) there are firstInstallTime and lastUpdateTime in PackageInfo.

To read more: How to get app install time from android

Answer 5

In my opinion, the best way to do this is to simply use the Firebase Realtime Database:

1) Add Firebase support to your app

2) Select 'Anonymous authentication' so that the user doesn't have to signup or even know what you're doing. This is guaranteed to link to the currently authenticated user account and so will work across devices.

3) Use the Realtime Database API to set a value for 'installed_date'. At launch time, simply retrieve this value and use this.

I've done the same and it works great. I was able to test this across uninstall / re-installs and the value in the realtime database remains the same. This way your trial period works across multiple user devices. You can even version your install_date so that the app 'resets' the Trial date for each new major release.

UPDATE: After testing a bit more, it seems anonymous Firebase seems to allocate a different ID in case you've got different devices and is not guaranteed between re-installs :/ The only guaranteed way is to use Firebase but tie it to their google account. This should work, but would require an extra step where the user first needs to login / signup.

I've thus far ended up with a slightly less elegant approach of simply checking against backed-up preferences and a date stored in preferences upon install. This works for data-centric apps where it's pointless for a person to re-install the app and re-enter all the data previously added, but would not work for a simple game.

Answer 6

After looking at all options in this and other threads, these are my findings

Shared preferences, database Can be cleared in the android settings, lost after an app reinstall. Can be backed up with android's backup mechanism and will be restored after a reinstall. Backup may not always be available, though should be on most devices

External storage (writing to a file) Not affected by a clear from the settings or a reinstall if we don't write to the application's private directory. But: requires you to ask the user for their permission at runtime in newer android versions, so this is probably only feasible if you need that permission anyways. Can also be backed up.

PackageInfo.firstInstallTime Is reset after a reinstall but stable across updates

Sign in to some account Doesn't matter if it's their Google account via Firebase or one in your own server: the trial is bound to the account. Making a new account will reset the trial.

Firebase anonymous sign in You can sign in a user anonymously and store data for them in Firebase. But apparently a reinstall of the app and maybe other undocumented events may give the user a new anonymous ID, resetting their trial time. (Google themselves don't provide much documentation on this)

ANDROID_ID May not be available and may change under certain circumstances, e.g factory reset. The opinions on whether it's a good idea to use this to identify devices seem to differ.

Play Advertising ID May be reset by the user. May be disabled by the user by opting out of ad tracking.

InstanceID Reset on a reinstall. Reset in case of a security event. Can be reset by your app.

Which (combination of) methods work for you depends on your app and on how much effort you think the average John will put into gaining another trial period. I would recommend steering clear of using only anonymous Firebase and Advertising ID due to their instability. A multi-factor approach seems like it will yield the best results. Which factors are available to you depends on you app and its permissions.

For my own app I found shared preferences + firstInstallTime + backup of the preferences to be the least intrusive but also effective enough method. You have to make sure you only request a backup after checking and storing the trial start time in the shared preferences. Values in the shared Prefs must have precedence over the firstInstallTime. Then user has to reinstall the app, run it once and then clear the app's data to reset the trial, which is quite a lot of work. On devices without a backup transport the user can reset the trial by simply reinstalling, though.

I've made that approach available as an extensible library.