I no longer have SF 4.5 but here's what I found out when I recently copied and up-loaded the installer for a game developer who needed to recreate some audio done with 4.5, but they got a 'disc required' message. I confirmed this and sent them discs. The disc could be copied and installed though.. there was no on-line copy protection but one still had to have the serial number. I did not try to mount a virtual disc (image), The early Sonic Foundry versions of SF were not available for download. (disc only).