But what was the origin of the invalid numbers? That's the teaser I kept reading for ...
The first result for "blurity serial number" points to https://www.trademarkia.com/blurity-77870929.html
Edit: Entering the serial number does indeed produce the easter egg dialog, with a coupon code that still works. BTW, there is a typo on the buy page 'regsitration'.
After I discovered people were doing that, I was rather surprised that they thought that the trademark serial number would be a valid registration key. I guess people don't read.
Edit: Thanks for the heads-up about the typo. Oops!
If they were modifying an existing valid key, it doesn't seem like people would keep using the same one. Unless people are downloading a keygen or something.
Any more hints?