Hi,

It’s notified in our documentation, we provide pre-match odds between 1 and 7 days before the match and we keep a 7-day history. Concerning the V1 the odds were always conserved but from next season the history will also be 7 days.
You can still access to the odds of V1 through V2 using this endpoints: v2/odds/{fixture_id} (although this is not in the v2 documentation because this feature is specific to v1 and is deprecated)