I forgot to mention that the Thai Immigration Officer gave me a small pink paper with the date. It stated that if you stay more than 90 days in Thailand, you need to go nearest immigration office to report or do it online. It is to confirm the location of your stay. If you stay less than 90 days in Thailand, you don't need to report.
I travelled to many countries and returned to Bangkok. All check-in counters never asked me for proof of visa because my passport allows me to travel to 177 countries without a visa.