In-house ads, if some of you may not be familiar with the term, are ads that are served in my apps of my apps. So what this means is that when people open Life Calculator app they will see an ad for Damn Lines! This is "sort of" free for me. Why sort of? Well they dont cost anything to display, which is great, but they cut into profits. And that's not so great.
Another thing is with the way AdMob handles in-house ads its very difficult to follow the progress of a particular app. So if before doing in-house ads I could easily see the number of impressions a certain app had, now I can't.
This is important for me as I like to track how my app is doing on a daily basis. It may not be crucial now, but in future, deciding when to run in-house ads because impressions are dropping would be rather difficult.