Sadhu for this gift of traditional cultural kind of Abhivadana (giving of respect, appreciation, welcome) by good wish.
A most famous Dhammapada-verse says: "For a respectful person by nature/character, who steady pays respect to those that who deserve respect, four Dhammas (phenomenas, qualities) increase (for him): longlive (actually "age", long age) (
āyu), beauty/esteem (
vaṇṇa), well-being/happiness (
sukha), power/strength (
bala)."
In Khmer, wishing long-life (ayu veng) is usually used at time of good by, wishing the other long-life when he leaves, is outside of ones possibility to support care for it.