Formal:
* อย่าลืม (yàa lūm): This literally means "don't forget," but it can also imply "never forget" in a formal context.
* จงจดจำ (jong jòt jam): This means "remember" or "keep in mind" but conveys a sense of "never forget" in a more formal and serious way.
Informal:
* อย่าลืมนะ (yàa lūm ná): This is a more informal way of saying "don't forget" and can be used with friends and family.
* จำไว้ (jam wái): This literally means "remember," but it can also imply "never forget" in an informal context.
* ลืมไม่ได้ (lūm mâi dâi): This literally means "can't forget," and it expresses a strong sense of "never forget."
Other options:
* อย่าลืมตลอดไป (yàa lūm tǎlòt pai): This literally means "don't forget forever" and is a strong way to say "never forget."
* เก็บไว้ในใจ (gèp wái nai jai): This means "keep it in your heart" and implies that the memory will never be forgotten.
The best way to say "never forget" in Thai depends on the specific situation and your relationship with the person you are speaking to.