Comment by LoriP

Timescale doesn't charge for any of its software. Revenue comes from providing hosting services that are optimized towards TimescaleDB and PostgreSQL at scale.

The code is source-available, license philosophy is explained in this blog post https://www.timescale.com/blog/building-open-source-business...

That includes the HA implementation, and I think someone else shared the docs for that. Hope this helps.