If you followed the directions here to obtain an Access Token from your own Facebook app to display an events feed then it has an expiration date of 60 days. Fortunately, there is an easy way to renew a token by following the directions below:
1) Go to the following link: https://developers.facebook.com/tools/accesstoken/
2) Find the name of the app you set up and click the Debug button next to the User Token for that app.
3) Click Extend Token at the bottom of the page.
4) Select the token and copy it.
Note: It will still copy the entire token even though it has an ellipsis (…) at the end.
5) Paste it into the plugin’s Settings page or shortcode to replace your existing token.