There is something missing about pricing and details about the "credits" > Is there a limit to the number of tweets I can reply to using the app? >

There is something missing about pricing and details about the "credits" > Is there a limit to the number of tweets I can reply to using the app? > > The app may have usage limits, please check with the pricing plan and detail. But the pricing page says one gets X credits. But what are these credits and how does one use them?