Okla. Stat. tit. 59, § 1013

The Construction Industries Board shall, upon proper application and payment of fee, register as a plumber's apprentice, and shall issue a certificate of registration to, persons who furnish proof satisfactory to the Board that they are sixteen (16) years of age or older and are enrolled in a recognized school or training course for plumber apprentices, or have arranged for employment as a plumber's apprentice with a licensed plumbing contractor. The certificate of an apprentice shall expire at the end of one (1) year from date of issuance, at which time the Board may issue a renewal certificate upon payment of the renewal fee.