There are 4 Seller
Tiers: Tier 1, Tier 2, Tier 3, and Tier 4.
Your Seller tier will be calculated on all fully complete orders which you've accumulated. There is no time limit for upgrading your tier, it will be automatically updated once the upgrade criteria have been reached.
Seller Tier Criteria
Tier 1: Starting tier
Tier 2: Sold 5 items
Tier 3: Sold 30 items or a total of 300,000 THB
Tier 4: Sold 100 items or a total of 1 million THB