Lex, as a fully managed Amazon service, would also scale automatically as the bots’ usage increased, meaning developers would only pay for the number of text or voice queries that Lex processes. Amazon’s goal with opening up Lex to the wider development community could give it an edge in its ability to compete with other voice technology, like Google’s Assistant or Apple’s Siri, for example. The company plans to take the text and recordings that people send to Lex-powered apps in order to improve Lex, and its ability to understand more queries, notes today’s report.

https://techcrunch.com/2017/04/20/amazon-lex-the-technology-behind-alexa-opens-up-to-developers/