There are plenty of duty free shops around the island including at the airport where all these are available at a reasonably cheap prices. For consumption in the island, you can buy as much duty free items as you want (like liquor, tobacco, perfume, cosmetics etc.) immediately after landing or entering Langkawi.
My personal Experience -No tax but rates are comparatively high which we can get in India in same price also.
Then why to carry unnecessarily from there .