How to store data permanently ?

Question

for example if you open any app and set password and after it if you again open the app, you won't be asked to set password again. Because it has been recorded by the app.
How can I make any executable file which will ask me to set password only once.

Answer 1

I think the simple method to your problem is to use files.
you can change files every time ..
..
fopen()
..

Answer 2

First, check if any of the apps has any such option (to save and reuse credentials), and if it does, but disabled, enable the option, if the app doesn't have such option I guess it's impossible.
Since you mentioned "any app/executable file" I assume you were not talking about a project you are working on, and that you don't have access to the source code to modify it to suit your needs.
And if you were talking web apps (I doubt you were), well, most browser has an option to save passwords, but I guess you already know.
Hth, cmiiw