Complex sentence: Some software developers use traditional USB flash drives as software license dongles that contain hardware serial numbers in conjunction with the stored device ID strings, which are generally not easily changed by an end-user.
Split into simpler sentences: Some software developers have come up with ways to use traditional USB flash drives as software license dongles. Usually this involves the USB device's hardware serial number in conjunction with the stored device ID strings, which are generally not easily changed by an end-user.