[Serie: All About Japanese Particles]
Note: -Kke follows V-ta and Adj-ta forms. In feminine speech, the verbs forms tend to be desu, deshita, and V-mashita.
1. Indicates a muted question in cases when there is information shared with an interlocutor that the speaker is trying to recall.
明日の結婚式は、何時に始まるんでしたっけ。
Ashita no kekkon-shiki wa, nanji ni hajimaru-n deshita-kke.
What time is the wedding going to start tomorrow? / The wedding tomorrow – what time was it going to start?
あなたの家はどこだったっけ。
Anata no ie wa doko datta-kke.
Now, where was your house? / Where did you say your house was?
2. Indicates that the speaker is remembering something from the distant past.
この辺に学校があったっけ。
Kono hen ni gakkō ga atta-kke.
Didn’t there used to be a school around here? / I seem to remember that there was a school around here.
あの人とよく酒を飲んだっけ。
Ano hito to yoku sake o nonda-kke.
Back in the old day I used to go drinking a lot with him./ I remember going drinking with hime quite a bit.
– Source: All about particles – A handbook of Japanese function words –