My gut tells me to be a little skeptical. The founder is listed as a Ginny Brancato of Cape Canaveral. She also has another site for humans
Welcome to Beloved Hearts where you can buy a resident virtual memorial there. That $25 fee is per year not a one time fee.
For the Beloved Hearts website they say a portion of the fee will go a grief counselling center. The Rainbow Bridge one is also only a portion of the fee going to an animal shelter.