Hi
The scripter is a solution to let users (and particularly users who made plugin) to quickly play, test, and do stuff with Krita.
As you might already see, once you’ve closed Krita, what you did on scripter is lost…
Yes 
In synthesis, solutions are:
-
Most basic: save the code you made in scriper in a file
You can save it anywhere you want on your computer, there’s no real “best place” for this it’s more a question of how you like to see stuff organized on your drive…)
When saved, load it and execute it in scripter each time you start Krita
Very easy for non-developers but really boring if you have to do it each time… -
Create a plugin
Plugin is the best solution for that: once created and installed, plugin is executed automatically when Krita start and then, you’re not bothered to do actions manually
What you want is “easy” to implement in a plugin (easy for someone who have some basic development skills, but for someone who never coded it could be hard to create a plugin…)
You can follow lessons about plugin on Krita Scripting School (especially lessons related to plugins) -
An alternative is to go here on this topic:
What plugins would you like to see?
Some people are asking for ideas to create new plugin, and this one could be interesting as it’s not really difficult to implement (and technical solution was already provided, just need to embed it in a plugin with maybe, a configuration file and a user interface…)
Grum999