To protect from spammers that use fake names in the messages they send via PartyLabz (unfortunately, it happens) we show 'PartyLabz' name so it was easy to understand that is not, for example, some bank name or whatever. That is how free event works.
In the paid events we instead of 'PartyLabz' name use the name of event host but still leave 'noreply@partylabz.com' email address to avoid spam filters to put such emails to 'Spam' folder (unfortunately, it still can happen as there is not 100% way to protect from spam filters). So, if you send invitations via PartyLabz your guests will see, for example, 'Host Name <noreply@partylabz.com>' but when they click on the 'Reply' button host email address will be used.