As mentioned by the Bangkok Post on September 25, 2017:

The Central Investigation Bureau (CIB) is stepping up its suppression of illegal drone activities, saying many drone enthusiasts don't realise they are required by law to seek permission before flying... 

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In Thailand, if your drone is more than 2kg or has a camera, you must register your drone. And to register it, you will need to pay insurance for it.

All information is available in English here:

https://www.caat.or.th/en/archives/27220