Well you might want to utilize the little amount of PPD options available (pay per download), but they might not work with an app that has little screen time.
If you provide a useful tools to users and think that they do get something worthwhile out of your app, the I’d try either a trial version that is time limited, or a trial version with limited features.
Either way the user has to pay for the full version.
You could even just offer the best features as In-App Purchases and provide the base functionality for free.
I think the best would be to put an interstitial ad right after the user sets the alarm. So that he has done what he wanted to do, and now he might be receptive for an ad.
(The worst would be to put an ad when the user wakes up )
You could also offer paid premium features, like ringtones, snooze settings or something like that.
What’s the advantage of your alarm app over the regular alarm?
Thank you A1ka1inE and Sasha for your suggestions. Makes a lot of sense and along the same lines I was thinking. With the number of free and good alarm apps available, it kind of becomes difficult to retain users while offering a limited period version.
Also, alarm apps have very limited screen time and user engagement, so my current ads aren’t doing very well.