I just enabled bitlocker on a laptop I have without TPM on Windows 8.1 Enterprise. I used the USB to store the key and entered a passphrase as well.
When the laptop starts, all what I need to do is enter the passphrase and windows starts. If I do not enter the passphrase and hit ESC, I am required to enter the USB, which stores the key. So, I understand here that the USB is for recovery purposes.
I do not understand the concept here. If I do not have the TPM module on the laptop, where is the key stored? and why am I not required to enter the USB key every time the computer boots? what does the passphrase exactly do in this case? I'm not complaining about the funcionality, I just do not understand the behavior or BitLocker