Yeah, a key detector...Each and every morning, when my wife and me are about to leave the house (running late as usual) and we just can't find her keys - I ask myself the same question; 'Does FL studio have a key detector??'
Btw, my wife said no, it doesn't have a key detector, but there's a parotte on box!
you can open a spectrum analyzer and look for the key when the sample "resolves". Sometimes i like to hum the sample and usually the key is the note that feels like its at home or when i resolves. Sorry if it doesn't make sense lol
It's really to your advantage to do it by ear. Just load up a basic sine wave and play through some octaves on the keys until you figure the note or notes. If you've got a musical ear at all should be pretty simple.