Used to express that one is trying to recall some information.
Verb-casual (plain) form + っけ?, い-Adjective + っけ?, な-Adjective + だっけ?, Noun + だっけ?
Long explanation:
The ~っけ? grammar point is used at the end of a sentence to express that the speaker is trying to recall some information or ask someone else to confirm the information. It can be used with verbs, い-adjectives, な-adjectives, and nouns.