Question GUI Toggle Deactivates On Window Close

I had a quick question regarding Unity Editor Windows and wondered if anyone could help me or point me to someone who could. I made a gui toggle but when it is selected and you close the window, the next time you open the window it is unselected. Is there a way to make it stay on if clicked?

Code (CSharp):

1. public bool DarkMode { get; private set; }
2.  
3. DarkMode = EditorGUILayout.ToggleLeft("Enable Dark Mode", DarkMode);
4.  
5.             if (DarkMode)
6.                 GUI.backgroundColor = new Color32(60, 60, 60, 255);
7.             else
8.                 GUI.backgroundColor = Color.white;

I wrote the code to change my text blocks to a dark grey if the toggle is selected