>Bottom line, if you create a class in code, it is created whenevery you run the code,

Just running the code that defines the class will do nothing. (it doesn't even put the class definition in memory- you have to SET PROCEDURE TO to make it available to instanciate).
The object is only created when you Issue CREATEOBJECT('myObj').

The object ceases to exist when all variables that reference it are released or go out of scope, or the container that it was added to is destroyed. (Or if the object is removed from the container with REMOVEOBJECT).