As per the response in Getting Duration using the new dateTime API you should be using
Period p = Period.ofYears(1);
It’s important to understand the difference between Duration (exact number of nanoseconds < 1 day) and Period (variable > 1 day).
Duration won’t account for leap days, daylight savings time or leap seconds, for example, and is intended for durations of less than a day, at most a few days.
So you should use Period instead.
Because different years have different number of days, if you want to find the number of days in a year, you need to specify which year you’re talking about.
If you want the number of days in a specific year, you can use
Year.of(year).length()
If you want the date one year from now, you can use
LocalDate.now().plusYears(1)
or
LocalDate.now().plus(Period.ofYears(1))
If you need the number of days between two dates, you can use
ChronoUnit.DAYS.between(start, end)
So to find the number of days to the date a year from now, you can use
LocalDate today = LocalDate.now();
long days = ChronoUnit.DAYS.between(today, today.plusYears(1));
If you want to see whether a membership of one year is still valid, you can use
Period membershipLength = Period.ofYears(1);
LocalDate membershipStart = ...;
LocalDate membershipEnd = membershipStart.plus(membershipLength);
LocalDate today = LocalDate.now();
boolean memberShipEnded = today.isAfter(membershipEnd);
boolean membershipValid = !membershipEnded;