This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 舏 is uncertain. It visually contains 舌 (tongue) on the left, but the origin and function of the right component are unclear.
舏 has no clear meaning, so a mnemonic is not possible. Focus on its shape: 舌 (tongue) beside a curved stroke.
For キュウ, imagine a tongue (舌) making a 'kyu' sound while curling: kyu -> キュウ.