Most of the multitude of kill-a-watt type plug-in energy monitors will give cumulative kWh since the monitor was powered-on.
The device you link to looks like a whole-household energy monitor. There is a current-sense clamp for each phase of electricity supply into the building. I've used two different models of these types of device and they both gave cumulative use (though obviously you can't directly track usage by individual appliances). They typically give a history of usage by day for the last week, usage by week for several weeks and usage by month for several months.
The Gateway is the heart of the TED 5000 series. It stores 60 minutes of Second-data, 2 days of Minute-data, 90 days of Hourly-data, 24 months of Daily-data, and 10 years of Monthly-data and provides the communications interface to your computer. Your real-time and historical data can be viewed on your computer by the Gateway's Ethernet connection and its embedded Footprints Firmware