PES 2008 is no longer officially sold by Konami on digital platforms like Steam. Modern alternatives like eFootball (the successor to the PES series) are available as free-to-play titles.
Draft report on (PES 2008 PC full version download Ocean of Games). Current Status and Availability
Websites like Uptodown still host legacy installers for older Windows versions. Risk Assessment: Ocean of Games (Ocean Igara) Download Pro Evolution Soccer 2008 1.0 for Windows