"30-day trial: This action cost me about 90% of my users. Many were angry and cursed at me on twitter. I agree that it is sad I did not say I was going to charge from the beginning, but I didn't know that I would be paying hundreds of dollars per month either."
Honestly I think the sense of entitlement nowadays is way too high, people use a product that is free and needed weeks or months of your own free time, and then complain about it when you change it.
I guess now it's too late :D
If anybody is interested the apk is here
http://goo.gl/6BxAZJ