Please help me to identify my plant.
Thank you for attaching an image. The plant is a verbena, most likely one of the recent hybrids commonly used as bedding plants in gardens and landscapes. It is a perennial which, depending upon the prevailing temperatures where you live, may survive for a number of years.
Because you mentioned Australia, I’m including this link to a plant profile for growing verbena there: http://www.abc.net.au/gardening/stories/s1866736.htm