https://www.theguardian.com/technology/2018/jul/05/defunct-jawbone-fitness-trackers-kept-selling-after-app-closure-says-which

When Jawbone liquidated its assets, its wristbands became useless without companion app

Fitness trackers made by the defunct wearables company Jawbone were still on sale at Amazon, Selfridges and Groupon more than a month after they were rendered useless by the closure of a companion app, according to research by the consumer magazine Which.