We understand the concern here at Wit. It's free because we no longer need to generate revenue. Wit developers spend time validating data that is critical to improve the models for the Wit community. When we joined Facebook in Jan 2015, we updated our Terms of service to mention that you can retrieve your training data if Wit closes at some point. FYI, the training data (expressions, intents, entities) is the critical component. The plan is to continue supporting and growing the product. The release of Bot Engine Beta a few months ago is a proof.