Albert Barnes Commentary 2 Kings 25:30

"and for his allowance, there was a continual allowance given him of the king, every day a portion, all the days of his life." — 2 Kings 25:30 (ASV)

Allowance - From the treasury, to enable him to maintain the lifestyle appropriate for his rank, in addition to his food at the royal table. Jehoiachin, until the day of his death, lived in peace and comfort at the court of Babylon .