This is the sim that I have in my 2nd sim slot. Unlimited data. Unlimited calls to other DTAC numbers (limited to 15 mins max per call). 60 mins of calls to all networks per month free. It's only 15Mbps speed, but that's more than enough for me for online shopping, banking, paying bills, google maps, LINE, Skype etc. When it expires, I just throw it away & get a new one. My other sim is my "permanent" number.
Lazada vendor is WPN Mobile, who I have found to be very good. They sell AIS and TRUE sim cards as well.