[Kailo]

How store Function in KeyValues or get function name from Function?
Or another way?
Please, help me.

[Potato Uno]

If I recall correctly, functions don't have names once the sp is turned into smx, and I don't recall any way of being able to execute arbitrary SM code via a string input.

You seem like you're gonna fall into the X-Y Problem trap. What EXACTLY do you want help with? (In other words, what are you trying to accomplish?)

[Powerlord]

What's the use case for this?

Traditionally, for calling functions in another plugin, you'd store it in a Forward to do it.