Regarding the update version 1.137.5872, it seems to be a specific patch for the game. However, I couldn't find detailed information on this exact version. Typically, updates for Forza Motorsport 7 include various improvements, bug fixes, and new content.
Some third-party retailers still have "unactivated" digital keys in stock. Ensure you are using a reputable storefront to avoid getting a revoked key. Regarding the update version 1
(released by the group CODEX) rather than an official game update from Turn 10 Studios. Regarding the update version 1.137.5872