Common law marriage cannot legally exist and therefore are you live with someone for 7 years, then you legally.
Cohabiting couples warned of 'common law marriage' myths
There are a number of methods by which these relationships are recognized in Australian law and they include the same entitlements as de jure marriage. The criteria for a relationship being accepted as marriage-like include cohabitation for at least the specified period, unbroken by excessively long intervals that are unexplained by exigent circumstances. For couples who live together in states with common-law marriages and want their wishes to remain unmarried to be unambiguous, partners can write and sign a document stating their intentions to stay unmarried. If a couple in one of these "committed intimate relationships" separates, a court can help equally divide shared property and assets. Since March 1, de facto relationships have been recognized in the Family Law Act Commonwealthapplicable in states that have referred their jurisdiction on de facto couples to the Commonwealth's jurisdiction.