Seven years is the American "Statute of Limitations." The "Clean Slate Act" is NZ. Australia has the "Spent Convictions Act" which comes into play after ten years. There are exclusions and conditions but they should be available on the net.
Victoria doesn't have a spent convictions regime but a number of other States do.
But, just because they are "spent" in your home state, this doesn't necessarily mean that they aren't on your BCI file and that you can therefore not declare them.
They won't be raised as priors in the event you are convicted of a further offence, but be careful signing a declaration that they don't exist. You need to check what the legislation says for the relevant jurisdiction.
What shouldn't happen is that they are revealed to the inquiry source.
Kaz