1) Access provider 2) Door opener 3) Entry provider 4) Hotel housekeeping need 5) It opens a lot of doors 6) It opens many doors 7) It opens many locks 8) It provides entrees 9) Master 10) Master key 11) Master lock opener 12) Master opener 13) Need for a restricted area 14) Opener 15) Opener for a hotel detective 
[n] - key that secures entrance everywhere
passe-partout noun key that secures entrance everywhere