Lord Kṛṣṇa, one's supreme master, is served by those who live in perfect chastity and renunciation, and who have given themselves entirely to Him.
zatāgo, a few years later, even those among the Vaisnavas who serve Krishna with mixed intentions,
desire is gradually destroyed and one becomes attached only to Krishna. Krishna
KKS
‘Pride and Prejudice’

Krsna reciprocates our service, and ultimately we become purified of all other desires. Therefore, after some
even in a person serving Krishna with mixed motivation, self-interest will gradually disappear
This person will become attached only to Krishna.
KKS
‘Devoted service’