We have similar problems on our Thinkpads running Win10 x64 Pro. Due to the botched MS 1803-1809 updates, we kept getting BSODs. I reset our PCs just keeping (most) personal files. Prey was among a list of apps uninstalled by the reset.
I went to C:\Windows\Prey\prey.conf and added:
Your account's API key.
api_key = XXXX
Your device's unique key.
device_key = YYYY
For YYYY I used the UUID
Should I have used the MOTHERBOARD SERIAL NUMBER?