Hi Eric,

I think you are referring to a Reviversoft product. The Licence code would not work if you have used it on any other PC previously.
If this is the case, then it is possible you might have upgraded your Windows or installed a fresh Windows copy on your machine and thus installed it again more than a single time.

If it is the same scenario, you can send an email to support@reviversoft.com stating that you are getting this message "Licence being already used on another PC".
An executive will surely help you out. Also, include your account details in the mail so that its easy to track your details at the earliest.

But if you have not received the Licence code itself, you can send an email to support@reviversoft.com asking them to issue a Licence code to you.

Regards,
Lokesh