There are 2 ways how to find the license key.
1st Option: Login to Customers Telstra Home Page
1. Go to www.telstra.com.au and login
2. Click on Internet
2. Under Anti Virus and Security Click on Manage
3. Under Licenses Click on Install
4. Once you click Install, notice that the link above will change. The last characters on the link is the license key.
2nd Option: You can find the license key on the About section of Telstra Broadband Protect.