Create a one-time order

Hello I would like to make a plugin or when we do the command /test for example and low it shows us a message but how to make it usable only once.

 

Assuming you mean one time forever, when the player runs the command, save their name to a file and check if their name exists in that file before executing the command's code.
pseudocode:

Code:

 if(isset(config, name)) 
 return;
else{ 
 your code
 config->set(players)[] = name
 config->save