Upon the liquidation of a domestic reciprocal insurer, its assets remaining after discharge of its indebtedness and policy obligations, the return of contributions of the attorney-in-fact or other persons to its surplus made as provided in AS 21.75.140, and the return of an unused premium, savings, or credits then standing on subscribers' account, shall be distributed to its subscribers who were subscribers within the 12 months before the last termination of its certificate of authority, according to a reasonable formula that the director may approve.