The Currant App does not have to be open for Currant Smart Outlets to operate or record energy usage. The rules that you set and your usage data are stored on the device.
Currant WiFi Outlets connect to the WiFi network in your home and transfer your usage data, so you can access it or control the outlets when you're away from home.
Currant Bluetooth Smart Outlets need a connection to the phone to transfer data, so you'll want to open the app periodically or keep it running in the background. Data can be stored for up to a month.