I read this fan-fiction a year ago.
Severus starts to have a better relationship with the Golden Trio, Neville and Lupin. But then Snape decided to be too risky and asked Dumbledore to remove their memories and cast it away. However, Dumbledore just seals it in flasks waiting for the right time to return them. Severus saved Lupin, Tonks and Fred during the last battle.