“Better Share Count” plugin counts the number of your posts’ Facebook share. By default, it connects to BetterStudio servers and collect the data and display them in your website. But Facebook has a limitation for number of requests per second. So sometimes this limitation reaches (because this plugin has thousands of users) and a notification shows up in WordPress admin area. This suggests you to use your own Facebook App ID & Secret code.
When you see this, our server limitation has reached and you need an independent access to FB for receiving your data.
How to Create Facebook App ID & App Secret
Facebook developers blog explains how to create FB App Id & App Secret.
How to Use FB App ID & App secret in Publisher
Now you have App Id & Secret, go to Publisher → Theme Options → Share Box → Facebook APP settings, here you can find corresponding fields for entering ID & Secret code.
Click Save Options and it’s done.