If I have a lot of old car key, can I use them to make a new key for my car?

what kind of old car keys? are they for BMW's

yes. there is car key programmer AK300 can judge how many keys the car ever had, and if a keys was used. A CAS can only make a maximum of 10 keys. Also you can tell whether the key was scrapped. We can use the AK300 to cancel the status of scrapped so that We can make the old to new . BMW AK300 can be used to unlock the keys, the keys can be recycled.