For more than one year, our game voxel invaders was present on google play as both a free demo version and a full paid version.
Recently we decided to remove the demo version and replace it with a free full version with ads.
To make it simple, we just updated our demo package with a new package incorporating the admob SDK.
In order to boost the new version, we also cooperated with app of the day (previously known as appturbo) to make a promotion of the game. On April 21, people who downloaded the free version of the game would get the full version for free, without ads. In exchange, 'app of the day' did a promotion on their website and to the users of their app.
The promotion was a big success in term of download: for the day the promotion was running, we had more than 60,000 users download voxel invaders.
If we do not consider the huge number of downloads from the day of the promotion. Before the switch, we had:
| demo | full ----------------------- | -------- |-------- Average download / day | 280 | 14 Average revenues / day | | 11 USD
And after the switch:
| free/ads | full ----------------------- | -------- |-------- Average download / day | 260 | 6 Average revenues / day | 90 USD | 5 USD
So we went from an average of 11 USD / day to an average of 95 USD / day, more than 8 times more!.
Interestingly, the average number of downloads of the free full version with ads is more or less the same than the demo version, even though I was expecting an increase due to the promotion. But maybe without the promotion the number would have decreased. It is hard to tell since we did both the promotion and the switch to a free+ads model at the same time.