Just recently upgraded from an Android 2.1 device (HTC Aria) to an Android 4.4 device (Moto X).

To enable the developer USB feature that allows installing and running (let alone debugging) programs, two things need to be done:

• Install the Motorola USB drivers (https://motorola-global-portal.custhelp.com/app/answers/detail/a_id/88481/action/auth)
• Enable the Developer feature on the phone:
  • Go to Settings
  • Scroll to the “About phone” option under the “SYSTEM” section and click the option 7 times (after clicking it 3-4 times you should see a message saying something like “you are X steps away from being a developer”)
  • After clicking it 7 times, you will “become a developer” and will then see a “{ } Developer options” entry under the “SYSTEM” section where you will be presented with a LOT more settings.