You can check your Stars balance on your app or on the website.
On App - The home page will show your current balance, please note that your yearly balance can only be found on the website.
Website- Log on to the website https://member.starbucks.co.nz/en/. This will bring you to your account summary, showing your total stars for your yearly spend, how far away from your next reward and also current rewards available. It will also provide the date of your anniversary, where the star cycle begins fresh.