If you need Mypornblocker, or any similar product, you failed as a parent. You should have been having ongoing, open, discussion with your children from the time they were 3 or 4 years old.
A problem with software like Mypornblocker is that context matters and the software houses never put enough work into the product to allow it to figure out the difference between a medical site, a nature site, and a porn site. As a general rule, the more spam sites are associated with a product, the worse the product is, and a quick Google search turned up lots of spam.
Put more work into your children and skip suspect software.