The first time you upload data from your device using diasend® Uploader, the software will ask you to verify your account, which means that you will have to enter your diasend® username and password. By doing this, the device will register automatically to your diasend® account.
If you want to double check that the device is registered to your account, you can log in and go to "My profile". The serial number will be shown under the right field. If the serial number is not displayed, you can add it to your account manually and then click "Save my information" to save the changes.