Australian Terrier puppies are born with their ears down. At approximately 7-8 weeks most puppies will have their ears standing erect without any help. Sometimes however, they need a little extra help to get them to stay up.
Teething or a tired puppy around this age or even older will at times have a flopped ear, that is normal.
If you want to help them by giving them a few simple but effective supplements, I have provided a link to those products below. We recommend Vitamin C and a Calcium supplement for many growing puppy parts as well.
If you find you need to tape your puppies ears, I have on very rare occasion as well, we use Nasal strips and Tear Mender glue. Shave the back of your puppies ears and put a small amount of glue on the back of the nasal strip and adhere to the the middle of the back of the ear down to just below where the ear and back of ear connect. Leave on 1 week generally it is enough time to train the ear to stand. Use care to gently remove the nasal strip as it will be quite attached.