Pardon

A pardon is a government decision to allow a person to be relieved of some or all of the legal consequences resulting from a criminal conviction.

Notable examples
In exchange for helping the Doctor in the Death Zone on Gallifrey, the Time Lord High Council offered him a pardon and a new regeneration cycle which he accepted. However, the events that followed led to the Master never receiving his pardon or new regeneration cycle. (TV: The Five Doctors)

Rigel was falsely accused of assassinating the emperor of the Leviathan Empire and fled to Gallifrey with Asher and Ella. After the twins came of age and took over the empire, they pardoned Rigel for his alleged crimes. (PROSE: The Twins in the Wood)

After the rightful government of Walter Fisher's planet was restored, he was granted a pardon which the Fourth Doctor and Leela attempted to deliver news of to him. However, Walter was assassinated before the two could find him. (PROSE: The Sooner the Better)

After Space Major Jon Bowman stopped Dalek X's plot at the end of the Second Dalek War with the help of the Tenth Doctor, he was given a full pardon by Earth Command for his previous actions and chose to retire on Earth. (PROSE: Prisoner of the Daleks)

In exchange for help in dealing with the Weeping Angel onboard the Byzantium, River Song was offered a pardon for the crime that had put her into the Stormcage Containment Facility, stated to be the murder of the best man she knew. At the end of the adventure, River suggested to the Eleventh Doctor that although she was being returned to custody, she may have done enough to earn her pardon. (TV: The Time of Angels/Flesh and Stone)

When the Doctor encountered River again in 1938 Manhattan, she told him that she was pardoned "ages ago" because the Doctor had erased every single trace of his existence from every database in the universe. As a result, there was no proof that the man River had killed ever existed. (TV: The Angels Take Manhattan)

In 1651, the Twelfth Doctor used his psychic paper to claim that Sam Swift had been pardoned by Oliver Cromwell himself in order to stop Swift's hanging. Though he was successful, Ashildr placed the Eyes of Hades on Swift's chest which killed him and opened a portal to Delta Leonis. Swift's death was reversed using a Mire repair kit and Swift remained free afterwards, suggesting that the fake pardon was enough to free him from further trouble for his crimes. (TV: The Woman Who Lived)