@Malembemalembe yes, you have to go back australia before the visa expires. according sa agent namin, ito ung details that he specifically note to us:
"once you have lived in OZ for four years you may have the option to apply for Austalian citizen. If not you will need to renew your visa as Resident Return VIsa. You will then get another 5 yrs of travel rights if you have spent at least 2 yrs in Australia during the initial five yr term. If you havent spent 2 yrs in Australia, you will be given a year's extension if you are able to prove 'close ties' to Australia such as having employment in Australia, financial ties, ownership of property, community ties (voluntary works), etc. At the end of the yr, they will access your renewal if need to obtain another 5 yr extension."
Australian Lawyer yung agent namin from Melbourne, so hope it helps.