I followed the steps and created a StackApp (registering a new OAuth app) and added a StackApp post as per question - My app has to be published first? But it's still under development
Now that my development is complete, my application can call Stack Exchange APIs successfully. Should I leave the StackApp post as it is and the app registration as it is? I'm looking to see if I need to do anything next on the OAuth app.

If the StackApp post is closed / deleted, will my application stop having write access?
– SO User Nov 18 '20 at 18:55