Free bars used to be a significant part of the world of
corporate entertainment. To a certain extent, they still are, but
senior management,
auditors and the
taxman are all liable to ask questions. The company will
pick up the tab, but may impose a
ceiling. If they do this, get your expensive drinks in early! Free bars (in this sense, with a
tab) are also common for
wedding receptions.
A free bar also provides a way of circumventing paying excise duty, if the drinks are home made (home brew, etc.). Duty becomes payable if the alcoholic drinks are sold, not if they are given gratis (this is true in the UK anyway). This does not stop the free bar charging an admission or a membership.