What does it cost to use the api on a commercial basis

[Michael_De_Marco]

1. what does it cost to use the api’s commercially?

2. how easy is it for a stock purchaser to make a purchase thru an app? Does it require them to
   give their banking account info? Ideally, they click a button give their credit card info and its
   done. Is this achievable?

3. How many requests can you make per second?