After you get the activation serial (key) of any EarMaster software from SudeepAudio.com, register it here

Follow the installation steps are explained here

Serial number recovery

If you are a registered user of EarMaster with a valid license, you will be able to retrieve your serial number in order to re-install EarMaster. This service is completely free and unlimited. Go here

For any other tech support, contact EarMaster here