Seems our issues fall on deaf ears. As I too am unable to register the product using the provided key (8NVCS-XGPZ4-7K7PB-9BGA1) with the same error as others have faced.
Out of character for Sharewareonsale.com keys, but this is very frustrating. Especially since SWOS hasn’t responded back with a fix, or even awknowledged the issue.