Yes. An active internet connection via WiFi is required in order to use the Hestan Cue app.
In addition, most Cue-enabled cooktops and cookware require a firmware (software) update via the internet before they can be used for the first time.
An active internet connection is also necessary when using the Hestan Cue app on your smart device as recipes, videos, and other multimedia get streamed on demand in order to prevent the app from taking up too much memory on your mobile device.
It is possible to use Cue-enabled cooktops without internet access after applying the initial firmware update, but you'll only be able to use it in manual (offline) mode. However, the Hestan Cue app cannot be used without internet access, so none of the guided recipes or "smart" functions would be available. In short, without internet access, the Cue-enabled cooktop could only be used as you would a traditional "dumb" cooktop.