Talisman: Prologue is no longer sold on Steam, but this key should still work. That said, it's 2020 now, and keys are not as eternal as we once thought they were. Therefore, alas, I must say this:

This key is an old key. It was purchased some years ago. To the best of my knowledge, it's as fresh as it was the day it was bundle-bought. I haven't used it, and I haven't given it away. However, many developers revoke unused keys these days for no reason and without warning, so it's not possible to rely on keys the way we did once.

If the key doesn't work, please contact me. If I can fix the issue I certainly will.