First of all, it was never unmaintained, and has two parts: interpreter and jit-compiler. The interpreter is rock-hard and was battle-tested in many production environments for years. There is nothing to do in it anymore[1]. Jit part is under active development. For one, among many others, they recently patched GC to remove the famous 2Gb memory restriction for LuaJIT. Jit was also always production-ready, but their sense of “ready” is too responsible, so their current version is beta3.

[1] yeah, the language doesn’t have to change and “evolve” constantly, if its roots were planned thoroughly.