Neural block

A neural block. (TV: Hell Bent)

A neural block was a small Time Lord device that wiped memories. The Twelfth Doctor tried to use a human-compatible neural block on Clara Oswald, given to him by a technician, to wipe Clara's memory of him, but Clara reversed the polarity using the sonic sunglasses and instead, the Doctor forgot most of his memories of Clara. (TV: Hell Bent) They were eventually restored by a glass avatar of Clara from the Testimony. (TV: Twice Upon a Time)

Madame Kovarian placed neural blocks on Melody Pond and the clones made from her DNA to ensure that even her experiments wanted to kill her, they wouldn't be able to follow through with it. (AUDIO: The Furies)