... おぼえはない => don't remember... N3
Position, perspective
いかに … とはいえ => What ever... N3
Things do not match the prediction
…とばかりはいえない => speaking of; when you talk of; when you say ~ N2
Ban
~といえなくもない => It can be said that ~ N1
Concession
~とはいえ      => though; although; be that as it may; nonetheless N1
てもらえないか => could you please ~ N3
Request
あえて~ない => Not trying to find a way N2
Emphasize
なければならない/なくてはならない/なければいけない/なくてはいけない/なければだめ/なくてはだめ => must N5
の[上「うえ」]では => As… N4
Situations and Experiences
ないことには~ない => unless you ~ N2
ないことはない => is not impossible to ~. N2
... ないものは ...ない => is not entirely impossible N3
Ability