What are you looking for exactly. Do you just want the PHP Redis extension or the Redis database server too?
In any case, we have no plans to add Redis support for free hosting. Most websites don’t have any use for it.
If you really want to use Redis in your site, you can still get a Redis server elsewhere and use the pure PHP predis library to interact with it. Sure, the native PHP extensions are faster, but performance is out of the window anyways if you use a Redis server in a different datacenter.