The commissioners shall serve without compensation for services as commissioners. The commissioners who are appointed to the commission and the commissioners who have been elected life members of the national conference, except those who are appointed by virtue of having served five years on the commission but who have not served at least twenty years in the legislative assembly, are entitled to be reimbursed, from moneys appropriated for that    purpose, for necessary expenses incurred in performing their duties at the rates provided in sections 44-08-04 and 54-06-09. Warrant-checks for expense reimbursement must be prepared by the office of management and budget upon vouchers submitted by the commissioners.