Why does my drive automatically lock after 7-15 minutes?
For Windows 8, the operating systems attempt to use USB Suspend in an attempt to reduce power consumption. When the drive is put into this low power mode, it will cause the drive to lock and return to a standby mode. If this becomes a problem, you can adjust the power settings on your computer or use alternative workarounds. for more information
For Mac OSX: Uncheck the “Put hard drives to sleep when possible” option in the power settings. For more information