Well damn I stand corrected. I couldn't find this information at all on the pages linked from the blog. Not sure if it's a huge omission or I just completely missed it. I'll have to re-check it in a bit.

It's prominently linked in the left side panel in the Getting Started section:

https://developer.lyft.com/

Third sentence of the post

> Using less than 20 lines of code, you can leverage the Lyft Button — which surfaces cost and ETA of a ride and deeplinks a user into the Lyft app (while earning revenue for every new user your app brings to Lyft).

which links to[0]

[0]: https://developer.lyft.com/docs/affiliate-program

Huh. Could that have not existed before I commented or am I really that blind? Oh well. I swear I read the whole thing.