Could you check if you which version of Buttonizer is installed/active?
Is it Buttonizer - Smart Floating Action Button (Premium)?
If you don't have the (Premium) tag at the end, then you might have the wrong version.
You can download the premium version in the email that you received your license code.
If you can't find the email, let us know! We'll send you a link to download the premium version of the plugin.