When a callback function in invoked, all of the variables within the callback function are created in its own workspace. When the function completes, all of those variables go away forever unless you save them somewhere. So every time you press the pushbutton, you need to store the current value as a vector that you save somewhere. A common solution is to store data within the "UserData" property of some graphics object within your GUI.
Here's an example that stores the vector within the UserData property of the numeric text field.
function ButtonPushed(app, event)
% store new value at the end of the vector
aap.EditField.UserData(end+1) = app.EditField.Value;
% reset the edit field back to it's default value (if needed)
app.EditField.Value = 0;
end
You can clear the vector from memory like this
aap.EditField.UserData = []; % reset vector
