He obtained a teaching license.
免許状を提示してください。
Please present your license/certificate.
免許状 and 免許証 look almost identical in writing, but 免許状 is the older, more formal term (e.g. for teaching licenses) while 免許証 is the everyday word for cards like a driver's license.
Compound of 免許 (license, permission) and 状 (document, certificate). The reading is standard on'yomi.