I'm using Google Appinvite for Android and it works very well: https://developers.google.com/app-invites/android/
But I realized that a certain time of day any user can send the invites and after a few hours back to work. I have a daily quota of submissions? If so how do I increase?
There isn't any specific daily quota, but it does have spam and abuse monitoring. Normal activity is fine and shouldn't result in any type of daily restrictions.