It's enabled by an envar as described by the hero who cleaned up the hack and ported it here: https://github.com/ferd/erlang-history
The hack was an old thing I had written at a hackathon over half a decade ago. It had little cost to regulars who had installed it at least once before. It relied on DETS and had transient issues with corruption of history files, but nothing major enough for anyone to take notice or get mad about it.
I myself ended up working on other projects once that one was good enough (including the search function with ctrl+r in the shell -- that wasn't there at first, and then things like rebar3 and other side projects), and nobody really ever took over or reimplemented a better shell history around it, nor took the time to port it to OTP.
I had also asked for help in the past for a better implementation that didn't rely on DETS, but not a lot of people were interested or knew how to proceed any better than I did. Eventually I just got tired and reimplemented it with the disk_log module and some log fragmentation and rotation to avoid dropping the whole file every time a limit was reached. It took a few weeks of review to get it in and so far nobody has complained about it.
I think the overall lesson is that the moment you have a quick hack to do the job, regulars get used to them, but forget about the beginner's experience where what you have to do is apply all the hacks at once and dear lord does it ever look janky then.
for the lazy:
Add `export ERL_AFLAGS="-kernel shell_history enabled"` to your profile and get shell history out of the box with #Erlang/OTP 20
(from https://twitter.com/mononcqc/status/877544929496629248)