I’m assuming you’re referring to the app that’s needed to make the watch communicate with your phone. On Android phones just download the .apk file from the internet and install it. (It’s no longer on the app store). You can find it here. = https://apkpure.com/martian-watch-alerts/com.martianwatches.martianwatchal... If you have an Iphone you may be out of luck.