I would hesitate to buy such a quantity of flaxseed oil. In his book "Fats that Heal, Fats that Kill", Erasmus says that flaxseed oil can be kept frozen solid in a freezer "where it will remain fresh for over one year" (p.304). That is valid for unopenned bottles only.
BUT, he also says that if that oil was not pressed in a dark, oxygenless and cold place and if that conditions are not preserved during the delivery from the oil-maker to your table, freezing your oil will just slown the deteriorating process of an already doubtful quality oil.