Apple announced Public Beta for both, macOS Sierra as well as iOS 10 when the two were introduced back at WWDC. For a good two month period, this Beta allowed Apple to iron out the issues that the enthusiastic Beta users faced and ensure that the final release was good. However, going from beta to the public release on iOS was a tricky one as it needed you to virtually wipe your entire iPhone or iPad away and get going from the start. However, if you are on a Mac and were one of those who signed up for Public Beta of Sierra going is much easier.
Even if you are on a Public Beta, all you need to do is to go to the Apple App Store on your MacBook and search for Sierra. You will see the update available as a standalone app. For our 2015 MacBook Pro, the update was about 4.4GB in size. Wait for the App Store to download the update and once done, it will prompt you to restart your Mac.
With this method, Apple basically just installs the OS all over again as if the Public Beta was just an older OS. Your data will be safe, though you are always advised to take a backup of your important documents and folders before you go ahead with the update on your machine. Once you have installed macOS Sierra, you will be able to use features like Siri on the desktop, unlock your mac using Apple Watch, iCloud Drive to create more space on your computer and much more.