What did Bod write on the witch’s handmade gravestone in The Graveyard Book?

After meeting the spirit of Liza Hempstock, Bod is determined to get her a headstone. He doesn't think it fair that she doesn't have one. The reason why Liza doesn't have a headstone is because, as a witch, she was denied burial in consecrated ground.
Bod hits upon a plan to steal a brooch from the Sleer, which he intends to sell to raise enough money to buy Liza a headstone. Unfortunately, the plan doesn't work out, as Bod is locked up in a back room by a crooked pawnbroker called Abanazar, who's determined to steal the brooch for himself. Thankfully, Liza's on hand to help Bod escape, but he's still unable to afford the headstone he promised her.
Bod gives back the brooch to the Sleer, who seethes triumphantly, "It always comes back." Though understandably disappointed, Bod is nevertheless still determined to do something nice for Liza. So he uses a big glass paperweight and some paint that he stole from Abanazar to create a makeshift headstone. On the paperweight he paints Liza's initials, "E. H.," and the words "We don't forget." As Bod's leaving the graveyard, he hears a voice say "Not bad at all." It seems that Liza's well pleased with Bod's efforts.