I don't speak French so I couldn't search if this feature was discussed already. sorry.
One of our users asks for an option to close a poll such that it votes can't be changed anymore but one could still link to the result as a reference. I see different options to implement this: a) Create an option to archive votes instead of deleting them at the expiration date b) Add a second Timestamp for "closing date" in addition to the expiration date
One could also think about it those dates should be editable via the administration interface.
Thanks for this great project!