King Power International Group
If you want the convenience of duty-free shopping, try King Power. You choose and pay for the items at the shop or online, then pick them up at Suvarnabhumi Airport when you depart Thailand (or simply take them with you). The most convenient location is King Power Rangnam on Soi Rangnam near the Victory Monument. You need your passport and an airline ticket, and you need to make your purchase at least 8 hours before leaving the country. The airport branch is open 24 hours.