This is answered in the FAQ: https://www.nextscripts.com/faq/#privacy-security

Question:
I got email from Google (LinkedIn, Facebook) saying “Your account was accessed from some remote location”, was that you?

Answer:
All our scripts are installed on your server and your server makes posts to your networks directly. When you make a post your server logins to your account on your behalf and makes a post. The location in the email that your account was accessed from is a location of your server.

Please confirm that it was you. It might take several times and then Facebook will stop asking.