Each licence code is valid for 12 months from the date of activation. Towards the end of the activation period, the emulator should provide you with a warning that your code is about to expire.

This should prompt you to log in and retrieve a new emulator licence code using the above process.

You can also check the expiry date of your licence code at any time by heading to My Account, clicking on the Emulators tab and locating the emulator for the model you are using. Against that model you should see a green box containing your emulator licence code along with its expiry date.