'Married in the Registrar's office according to 7 and 8 Victoria C 81 by licence'
"7 and 8 Victoria c 81" is the Marriages (Ireland) Act 1844. "7 & 8" are the years of Queen Victoria's reign during which the legislation went through Parliament and then received the royal assent. Victoria became queen in June 1837. The end of her 7th regnal year and start of 8th regnal year were in 1844.
"7 & 8 Vict. CAP LXXXI An Act for Marriages in Ireland: and for registering such Marriages (9 August 1844)"
Coincidently, another Parliamentary Bill which received Royal Assent on the same day was "Roman Catholics Penal Acts Repeal".