Deuteronomy 12:19

Take heed to thyself that thou forsake not the Levite
By withholding from him the tithes appointed for his maintenance; or rather by neglecting to take him with him in order to partake of the feast or entertainment before spoken of:

as long as thou livest upon the earth;
so that it was not one time only, but always; whenever he ate these holy things before the Lord, as long as he lived, he was to be careful he had the Levite with him, for a reason given, ( Deuteronomy 12:12 ) .