The installation instructions explicitly state that it's necessary to run HICSOAP in Administrative mode when entering the unlock key. Not everyone does this and a common consequence is that you may be prompted for the unlock code every time you start the program.
For Windows Vista, 7, 8, and 10, UAC should automatically elevate you to have administrative rights. However, it's possible that that doesn't happen. One way it could not work correctly is if UAC prompting is turned off.
Do this to get the unlock key to work permanently.
Close the program
Right-click the program icon and select "run as Administrator”
On the Registration Screen, enter your registration info and unlock key. Then press OK and NOT "Try Pro" or "Try Deluxe"
After getting all the way into the program, close it.
Now start it like normal.
Another possible cause of HICSOAP requiring you to enter the unlock key every time you run the program or every day is aggressive security software. For security reasons, it is possible to overwrite and replace the windows registry on a regular basis. Since the unlock key is stored in the registry, if the registry is replaced then the entering of the unlock key is effectively undone. This is not common.