According to a chat between an Asus rep and a customer, Asus is working on Android 5.1 Lollipop update with the Zenfone 2 ZE550ML. The build is in final testing phase according to the conversation. You can watch our Review of the Asus Zenfone 2 ZE551ML below.
ZE550ML is the base variant in the Zenfone 2 series and comes with a 720p display, 2GB RAM, 16GB storage. It runs on the Intel Atom Z3560 quad-core processor. The top Zenfone 2 variant with 4GB RAM has yet to get the update, but the signs are good since Asus is working on updates.
Source: The Android Soul
