Door supervisors working in Bridlington were targeted by Humberside Police and the Security Industry Authority.
The operation was carried out to address concerns about security in the area and to gather intelligence.
Sixteen individuals working at seven venues were inspected with all found to be in possession of a valid SIA licence.
However, five warnings were issued to door staff for either failing to display the licence or failing to notify the SIA of a change of address, which are breaches of licence conditions. The police are carrying out inquiries at two venues that have in-house door staff to determine if management are appropriately SIA-licensed.
Neil Diamond, the SIA’s head of investigation, said: “This joint operation has highlighted the benefits of partnership working and sharing information.
“It is important the door staff and those deploying them are operating legally especially as we are approaching the busy Christmas season.”