key sticking in deadbolt lock

Answer 1

If other keys work, then it is the key, but if all keys stick, the problem is the lock.  For the lock, try graphite spray or wd-40.  If that does not do the trick, the tumblers may be worn out and you should either replace the lock or have it rebuilt by a locksmith.
   If just one key sticks, polish the sides of the notched part with an emory board (not the tips, just the sides).  If that does not do the trick, the key was cut poorly and it is best to start over.

Answer 2

Here is the only strike plate in the world that fixes hard-to-turn or “sticking”deadbolts for good. PLUS, it helps resist against kick-in burglaries.

www.sure-strike.com