Android Wear is still pretty new, but a rather prominent issue has already surfaced. Wear apps are usually downloaded from the Google Play store via mobile phone, after which the apps are automatically installed on a paired Wear device over Bluetooth. But a bug in Google's app encryption prevents paid apps from being installed on Android Wear devices. The app encryption feature was added to the Play Store in order to encode paid apps with a device-specific key, making the apps more difficult to crack and thus deterring piracy of the apps. But due to the app encryption, Wear devices are unable to extract the file of the encrypted APK and thus the app installation process is aborted whenever it concerns a paid app.
Source: Android Police