just a few examples:
189 visa granted 2013 = you have up to 2018 to travel in and out of Australia without the need for RRV.
2018 = if you're staying in Australia and not plan on going outside the country, then you don't need to do anything. Your 189 is still valid. But if you need to go outside Australia, then you need the RRV. Depending on the length of your stay (and absences) during the 2013-2018 period, RRV is granted for 3 month (?) to 5 years. If you meet the maximum residency requirement, then it's 5 years.