The first step of integrating in app purchases plugin into a cordova app is to decide what kind of products you want to offer and setup these products on iTunes Connect and Google Play.
In mobile apps it is frequent to have a combination of the following screens:
Testing Cordova in app purchases is different on iOS and Android and requires some setup on both platforms. In both cases, make sure you are testing in-app-purchases on an actual device and not on a simulator.
I have a small Makefile that I use to automate signing, installing and running builds on an Android device.
If you have multiple servers running your application, you will need a way to monitor your logs in a remote and centralized place and have all the servers report to it. There are a lot of remote logging services, such as loggly, papertrail, etc. I've tried many of them but ended up choosing CloudWatch Logs.