Need to perform a hard re-set of my device

Hi there, I bought the chinese dictionary and phrase book, and due to some other issue on my HP IPAQ, I need to perform a hard reset, i.e. back to factory settings. This will mean that the software will be deleted from my ipaq since the HNH s/w didn’t come with the IPAQ when I purchased it. Could you let me know what I need to do once I have done the hard reset in order to get the HNH software back on my device? I still have the email I got from HNH after purchasing the s/w, which includes the license key etc.