Click on Buttonizer -> Account in the Wordpress Dashboard
Click on Join the Beta program to sign up for the beta program, and confirm in the dialog that will appear.
Reload your page and you will see a blue button appear with Install Update Now to download the newest beta. You can also update the plugin within the plugin list.
You have now been signed up for the beta program and will receive the newest beta whenever we release them!
You can leave the beta program in the same way, by unclicking the Join the Beta program checkmark in the Accounts page. You can then