The Asus ZenWatch based on Android Wear has stated receiving the Android 5.1.1 update. This update is slated to bring a lot of great features including support for always-on apps, new hands-free gestures for navigation through the user interface and Wi-Fi.
Though the Android 5.1.1 update will bring support to Wi-Fi, the Asus ZenWatch does not have Wi-Fi radios. If you own a ZenWatch, you will receive the update that will bring these aforementioned features. If not, you can check for the same by swiping down the watch face to go to Settings -> Go to About -> System Updates.
You can also download the OTA file and flash it manually if you can handle it. In end, your ZenWatch should run on Android 5.1.1 with the Android Wear version number 18.104.22.1680765 and Google Play Services version number 7.3.36.