In this discussion, 365 days and 1 year are different. Please use a correct term. When a leap year is involved, 1 year and 365 have different results.
IATA uses '1 year' or '12 months'.
So, a ticket of the first flight on 1st Feb 2016 is valid through 1st Feb 2017 (including 1st Feb 2017, 366th day after the day of issue).