this one is old... its same like on c1 without weight limit, where u put amount to buy 1kk keys, its show u gonna buy them for 1,5kkk~ and then dont press ok, then again drag another 1kk keys and u gonna buy all keys for 0 adens, its old bug, and not working on servers, but u get ban/jail for this in L2J(oke) servers... or DC on L2OFF servers.