I believe it's for short term rental in condos? (link - https://www.airbnb.com/help/article/2208/responsible-hosting-in-thailand - "Thailand has laws and regulations that may affect short-term rentals. Please check the relevant laws and regulations for compliance"

https://www.khaosodenglish.com/featured/2018/06/24/thai-law-case-closed-on-airbnb-heres-why-it-wont-matter/ - "The prescribed punishment under the Hotels Act for operating a hotel business without a license is one-year jail term and a fine not exceeding ฿20,000 (USD$645) on top of a daily fine not to exceed ฿10,000 per day as long as the violation continues."

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Again, please note I'm not sure exactly how reliable this is aswell as it does seem to be a bit of a grey area, however even in my condo (tonglor), there are frequent signs around (lifts, etc), saying about renting out on a weekly or monthly basis is illegal and there are fines for 10000+ (although not sure how strictly this is enforced, ofcourse)