It is always a good idea to back up your "save" folder located in your Documents to prevent losing Master League or Become a Legend progress. How to Install PES 17 Data Pack 1 on PC

PES 2017 Data Pack 1.0 (released October 27, 2016) is a free downloadable update that primarily refreshes the game's realism through visual and roster updates. On PC, this update is typically delivered automatically via Steam or through various community-hosted archive sites if you are using an older version or specific patches.

Data Pack 1 is compatible with the standard PES 2017 PC requirements: Windows 10, 8.1, 8, 7 SP1, or Vista SP2.

The early response on PC forums (Evo-Web, Reddit’s /r/WEPES, Steam Discussions) is cautiously positive.