Snapedom

Another thought - what if Snape had actually managed to survive the war? There would be no one to clear his name, and he'd have to live like a fugitive. No one would believe that he was loyal to Dumbledore after killing him.

Would Dumbledore have spared a single moment of concern for Snape's welfare post-war? It would certainly have been risky to leave behind irrefutable proof of Snape's loyalty, but without it Snape would be hunted by a dog until he was captured and either given the Dementor's Kiss (if the ministry can still find any Dementors that obey) or sentenced to life in Azkaban.

Rowling has stated that it is possible to defeat Veritaserum through various means, including Occlumency, so even a truthful testimony from Snape would not be believed. Pensieve memories cannot be tampered with, but the Wizengamot would find some way to claim that they were fabricated.

Dumbledore never seemed to genuinely care about his puppet while he lived. He may have a very cursory concern for Snape's well-being, but if Snape was killed or incarcerated for life, that would just be like tying up a loose end.