っけ

「っけ」is often used in conversations, placed at the end of a declarative sentence to:
1. Confirm or remind oneself or others about something not remembered clearly.
2. Express nostalgia or reminiscence about something.
「っけ」can also be used with a question word to ask a question, aiming to inquire about certain information from oneself or others.
「っけ」can also be used in polite/formal language, and can be used when speaking to teachers, senior colleagues in a company, etc.
Information about the present or future can also be expressed in the past tense when combined with 「っけ」, with the meaning remaining the same.