Niconico points expire after a certain amount of time
Your unused points (either purchased or gifted) will expire and can no longer be used after the expiration date.
◆When will my points expire?
Points earned (purchased or gifted) between October 1st of a given year to September 30th of the following year will expire on September 30th, the year after that.
For example,
[Date of acquisition] (mm-dd-yyyy)
Points purchased/earned between 10/01/2017 to 09/30/2018
[Expiration date] (mm-dd-yyyy)
09/30/2019