This is my second mini PC and I am a happy customer.  Upgrading the RAM with a second DIMM was easy as the installed RAM is only in one socket, as was fitting an additional  SSD drive using the SATA interface.It comes with Windows pre-activated with a digital license.  There are no problems with this.  I tried to upgrade the pre-installed M2 SSD but could not get Windows to re-activate after a fresh install, even after getting new product codes from Brett.  Recommend therefore making a Windows recovery disk and upgrading by cloning the original drive in a 2-socket M2 external bay if that's ever needed