Raymond will give you this when you're ready to open the tower, generally after your've
defeated the golem and collected the ninth sephira key

My last key was on the Crypt.

where i get the key i n the grypt?????

man it is a litlle difficult but it is simple go and find it :P κιαν εισαι
ελληνασ εισαι πολι αναπηρο

talk to mikul he has it

The order you get the keys in isn't hardcoded, you can get the keys in a different order
so it's impossible to tell you where YOUR last key is. The keys are all named, ask for
the location of the specific key you're looking for or look for a game walkthrough to find
the answer. For most people the last key they will get will be given by Raymond as they
progress through the main plot.