Originally Posted by
stifle
Where security checks are conducted at the gate (this applies, for example, in AMS for many non-Schengen flights), in most cases the salespeople in the passenger-only area will place liquid purchases in a sealed tamper-proof bag, which can then be taken through security and on board.
It also means that if you buy at one EU airport then transit another AIRSIDE you can take the liquid purchases through security as long as it remains in the tamper proof bag, you have the receipt and you bought it in the previous 24 hours.