Data Saving After Closing

Question

I am trying to make a program and for it, I need to save data when the program closes and access that data when it opens up again, Is there a way to do this?

 

For example, if I say that the variable userAmount is equal to whatever the user puts in a text box and a button that says "Get User Amount" is there a way to remember what number the user put in the text box after closing and re-opening the program?