Please make sure you create a Stardock account and use the Stardock account to logon to Demigod. Here are links that should help you create/manage your Stardock account.
Create Stardock Account and register Demigod: https://services.stardock.net/accounts/createaccount.aspx
Register Only (if you already have a Stardock account): https://services.stardock.net/accounts/registerproduct.aspx
My Account Downloads Page on Stardock Store: https://store.stardock.com/myaccount/products
Reset Stardock Password: https://services.stardock.net/accounts/resetpassword.aspx
Note: With the version of 1.30.164 (Available via GameStop) , there is a bug where saved passwords are failing. We are aware of the issue and will be issuing another update in the next couple of days to address the issue. If you are still having troubles logging into Demigod with your Stardock account, use one of the above links to assist you with logging in.