Who said "I know what it's like to ache for something."?

I know what it's like to ache for something. - K

"I know what it's like to ache for something."

"I was born, but not alive. I exist to serve."

"Love is a memory. Memories can be implanted."

"To know yourself, you must first know what you are."

"Happiness is a luxury for those who can afford uncertainty."