The veteran cape (15 year) is one of the Capes of Distinction, available to accounts that were created on or before 19 April2009. Accounts which are at least 15 years old can purchase the 15 year veteran cape and hood from Hans at Lumbridge Castle for 150,000 coins.
While the 15 year veteran cape was released in-game on 6 February2017, it was not obtainable by any player until 23 February 2017. This coincides with the date membership was released as Jagex did not track account creation information before this date.[1]
References
^Mod Balance. 15 Year Cape - Clarification. Jagex. 2016-02-06. (Archived from the original on 2017-02-15.) "The 15 year cape will be available to players from the 23rd of February – this date marks 15 years since we first recorded the creation of accounts in RuneScape (and don’t worry about leap years as the RuneScape game ignores them)."*