Oracle 18c

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create table test2
( productid varchar2(20)
, productlife number );
insert into test2 (productid,productlife) values ('A',5);
1 rows affected

insert into test2 (productid,productlife) values ('B',2);
1 rows affected

with
    function list_years(n number) return varchar2 as
        end_year   date := trunc(sysdate,'YYYY');
        start_year date := add_months(end_year, (n*-12));
        y date;
        years_list varchar(200);
    begin
        for i in reverse 1..n loop
            y := add_months(sysdate, -12 * i);
            years_list := years_list || to_char(y,'"Y"YY"|"');
        end loop;
        
        return rtrim(years_list,'|');
    end list_years;
select productid
     , productlife
     , list_years(productlife) as prefix
from   test2


PRODUCTID
PRODUCTLIFE
PREFIX


A
5
Y15|Y16|Y17|Y18|Y19

B
2
Y18|Y19