Is seeking forgiveness one hundred times also part of the evening remembrance (adhkar al-masa'), and is it permissible to publish the morning and evening remembrances that include seeking forgiveness one hundred times, knowing that it was mentioned in a hadith from the Prophet, peace and blessings be upon him, even if not in a firmly established form?

Seeking Allah's forgiveness (Istighfar) one hundred times is part of the morning remembrances (Adhkar al-Sabah). This is confirmed by a hadith (definition) from the Prophet, peace and blessings be upon him: "I have never woken up a morning except that I have sought Allah's forgiveness in it one hundred times." As for it being part of the evening remembrances (Adhkar al-Masaa'), there is no evidence to support that.