I have a bug in V0.4RC3 where the lower dungeon key is in my possession but it when I try to use it it says I don't have it. I think this condition happened after I accidentally chose it as a gift to the Princess. Hope that helps.
Viewing post in The Princess And The Tower (18+) comments
Thanks for the report. Tracked as
| CR-0139 | Bug | Cellar / dungeon key accidentally giftable, blocking game progress |
Codewise, that seems unlikely, as all keys are unsellable and specifically ungiftable. Your game state might be corrupted.
Nevertheless, I will look into it for next release.
P.S. You might want to D/L v0.4RC4 as that fixes one critical quest bug. Savegame compatible if you use saves made _before_ your first night visit at Irith.
Or you may wait for V0.4.1, which will be released 16.06. on patreon. Well worth it imho.
Public release of that 0.4.1. content (mostly NSFW cutscenes and QoL features) will be with the next public release M07.