There are two ways to check if there is a new version of the extension:
1. (**Recommended**) You will receive a notification about a new version of the extension in your website's admin panel. In order to be able to install the new version of the extension you should activate the extension. How to activate the extension you can read in the documentation inside the downloaded archive. If you don't have an update notification in your website's admin panel - it means that the update website is deleted from database or updates are not checked by the Joomla system. In that case you have to manually install the extension (like in the first time).
2. Check the extension page on https://allforjoomla.com/extensions and see what is the current version at the right part of the screen. Then check what version do you have installed on your website. If the installed version is different from the current, you should update it. How to manually update the extension, you can find in the Help section.
Also, you can subscribe to receive an email notification when the new version comes up. In order to do that, go to your account and check the "Notify me by e-mail when there is a new version of this extension" checkbox below the extension.
Please note! In order to have the extension working and also to have new functions, you should always use the latest version of the extension. More about it here: "Why do i need to keep the extension up to date".