The word for today is…
shot-clog (noun) – A person tolerated only because he pays the shot, or reckoning, for the rest of the company, otherwise a mere clog on them.
Source : The Free Dictionary
Etymology : The shot in shot-clog refers to a charge to be paid. It’s a cousin to, and synonymous with, scot, a word likely only familiar to modern speakers in the term scot-free, meaning “completely free from obligation, harm, or penalty.” The origin of the clog part of shot-clog is less clear. Perhaps it’s meant to draw a parallel between a substance that impedes a pipe’s flow and a person who impedes a good time; or perhaps companions’ tabs accumulate before the shot-clog as so much dross in a clogged pipe, while the shot-clog yammers on unawares. The 17th-century playwright Ben Jonson was particularly fond of shot-clog, and while the word is no longer in regular use, it might work for you as a suitable old-time insult for that person in your party who is fine to have around so long as they pick up the tab.