See this -->
PRO-97 Software - Win97 - Data Management Software for the RadioShack PRO-97 and PRO-2055 Multi-system Trunking Scanners
This info had to be accepted when you registered (the button to continue said "I acknowledge and agree to the above terms" even).
I kept my original emails, forwarded them to a second email account, printed them out and kept the hardcopy in my files. I recommend something similar to others to prevent the dreaded "I lost my key and can't reinstall" issues in the future. The $25 registration fee isn't that much and much less than having someone extract the key from your old hard disk if the damage is serious. If they can somehow get the software to run on your old computer (or boot from the hard disk on a different one and run it there) you may recover the key using the Help; License Key menu item.
If it helps, the email I got was sent from "From: "Win97" <Win97@starrsoft.com>" with the subject of "Subject: Win97 Registration Info for " followed by my email address. That email and the confirmation email were sent a few mins apart, but from different addresses (confirmation was from "From: "Don Starr" <don@starrsoft.com>").