As is free in WA is not a good excuse not to apply for it. Mine expired in December and I re apply.
Custom actually called the phone on my parcel and asked about the item.
It was held in Melbourne not Perth.
I was actually unlucky as my permit was not in hand yet. But I gladly told them I can forward my email that I have applied from the WA police department with the form application and the dated time of email. Gave them the email and they release it to continue to Perth .
When it did reach Perth I actually got the permit following day but it was no longer needed as they checked with the WA police.
Had the item misb not open but can see the parcel box stated it cleared custom.
My application now last till July 2019 and after I need to apply again if I want to buy another Megatron.