Hosts are urged to ensure doorstaff display their licences correctly after recent checks showed some breaking the law by having badges concealed under clothing.
That followed a check by the Security Industry Authority (SIA) and council officials in Kettering, Northamptonshire.
All 11 doorstaff checked at six pubs and bars had valid SIA licences, although a number breached licence condition because their badges were hidden under clothing.
In addition, one door supervisor's licence expired that day but he had failed to submit an application for renewal.
Jacquie Parker, SIA head of investigation said: "It was encouraging to see that all of the door staff held the necessary SIA licence. But operatives must ensure that they comply with all licence conditions - including displaying the licence at all times while working.
"Door supervisors are also reminded that they must renew their licence in good time before the old one expires, as there is no grace period between licences."
Cllr Alan Pote, responsible for public protection at Kettering Borough Council, said: "The council were pleased that very few problems were found during this joint operation but would remind businesses of the importance of meeting their obligations, which help to keep staff and customers safe."