Thanks to Stardock Support my login problems is now solved.
I have two registered accounts on Stardock as mentioned before since my PayPal email is different than my other email.
So I had problems with logging in and even merging the accounts didn't work.
The issue was that for some reason I had another email listed under my email.
Stardock Support merged them and I am able to login successfully now.
Cheers @ Stardock and especially Ken Janeczko