Sometimes, before releasing the public version, we publish a test version with the latest functionality.
This is for testing purposes, so don't enable it if you need a stable release.
To enable the Beta version, after you register your copy, you will find new settings in the License tab:
Fill the checkbox and save your preference.
Once you have activated it you will be automatically informed by WordPress if there is a new beta version, and the installation procedure will be the same as the stable version.
To quickly get the new beta release go to your Plugins archive page and click on "Check for updates". All beta version will have a '-beta' suffix.
Disable Beta Release
You can disable whenever you want the beta version simply by removing the check from settings.
If you get a beta version installed you can Rollback to the previous version, or update to the newest stable version if available.