Jawbone may have switched gears to medical devices, but there are some Up fitness trackers still out there. Those who use the Up4, Jawbone's most advanced tracker and one of the last it debuted before pulling out of the consumer-wearable market, won't be able to use its NFC payment feature for much longer. American Express customers who paired a card with their device are receiving notices that the partnership will end on January 31, 2018; the Up4 will no longer be able to make payments using American Express cards after that date.

The notice states that American Express will automatically disconnect the paired American Express card from the Up4 device on February 1, 2018, if not done by the user beforehand. To disconnect your American Express card before the cutoff date, go to the Amex Payments section of the Up4 app, tap "Manage," and then tap "Disconnect." American Express will be issuing a $10 credit to these accounts once the partnership officially ends.

Jawbone had a partnership with American Express that allowed Up4 users to pair an Amex account with the device to use with contactless payment readers. It worked well when the Up4 first debuted back in 2015, but it was relatively limited because users could only pair an American Express card to the device. Other contactless payment systems, including the new Fitbit Pay on the $300 Ionic smartwatch, allow for more than one connected credit card or bank per account.

It's not surprising to see a partner-based feature like this end for a Jawbone device. For the past year, Jawbone's wearable efforts have been shrouded in confusion. The company stopped selling its Up fitness trackers on its website and reportedly began raising money to make the switch to medical devices rather than consumer. Jawbone hasn't released a new consumer wearable since, but it also hasn't released a medical device, either.

Jawbone users had a recent scare when many experienced troubles syncing devices with the mobile app. Many feared that meant Jawbone may be shutting down its servers, but a Jawbone Health representative told Wareable that the problem wasn't a "widespread issue" and that they were working to fix it.

Jawbone was once one of the biggest consumer wearable companies, rivaling Fitbit just a few years ago. Rumors swirled of Fitbit acquiring Jawbone at the beginning of 2016, but, if true, the two companies never could come to a deal. Jawbone saw its marketshare dwindle with the rise of smartwatch popularity and products including the Apple Watch and Android Wear devices. The company has been unofficially out of the consumer wearable space for a while now, and it's unclear how long the company will continue to support the Up fitness tracker devices still on people's wrists. Ars has reached out to Jawbone for comment.