A woman buys a mask that changes her identity from a shop run by an old man. At the end she returns to the shop but a younger man is running the shop and says no-one else has ever worked there. Ends with a shot of a mask of the old man in the shop window.
I saw this on TV in the UK late 80s/early 90s.
It sounds similar to an episode from the 1st season of “Tales From the Crypt”(1989), it was called Only Sin Deep. The ending is different from your description.
I don’t think that’s it, I remember it having a 50s/60s feel, shown in the middle of day on BBC2 (I think).