for the life of

for the life of (one)

Despite one's best efforts; to any degree. I can't for the life of me remember where I left my keys! For the life of her, she just didn't understand people's obsession with selfies.
See also: life, of

for the life of (one)

Though trying hard: For the life of me I couldn't remember his name.
See also: life, of
References in periodicals archive ?
"The amount of premium you pay goes into the policy design, especially on a traditional policy because you know you have a fixed premium often for the life of the contract.
For the life of every disciple casts a shadow across the lives of countless others, and each of our lives will either be an encouragement, inspiration, or guide for those who come after us.