The noun dates from 1940 in its meanings 'material help given by one country to another' (
Christian aid, foreign aid, Marshall aid, etc.), and took on a further use as the second element in the names of occasions organized to raise money for charitable causes (
Band Aid, Fashion Aid, School Aid, Live Aid, etc.). The use was triggered by Band Aid, the name of a rock group formed by Bob Geldof in 1984 to raise money for the relief of famine in Ethiopia.