Lately, I have had several bad experiences with programs downloaded from GOTD expiring shortly after installation. Hippo... Is one of those programs. It expired on the day that it was installed. When I discovered that the program had expired, it was several hours after the Hippo... GOTD offer ended. By then it was too late to try to download and re-register the program and investigate what had happened.
I ran the program only one time and then it was expired. I was sorry that I missed getting to keep the Hippo editor because I have lost all of my other ones. At the time I thought that the problem had to have been my fault - even though I could not recall anything that I might have done to cause the program to expire.
Robert's post brings an interesting point to the surface. Perhaps the program's expiration was not something that I did wrong.
In the case of the other GOTD programs expiring (XTweak comes to mind) I felt that the XTweak program's expiration was deliberate. I seem to remember while the offer was going on a person, "describing himself as being from the developer's company", talked about the fact that there was no difference in the XP and Vista programs even though each program had its own name and download. I believe that he also said that the unlocking code would "be good forever". Am I wrong on this?
Other than premeditated short-sighted greed, I don't understand why a developer would distribute a bogus offer. I doubt that many users would purchase a program during the short life that it had. After having a program expire for no reason I would never buy anything that developer had to offer.