Set up a programme
Decide who controls pests: a qualified contractor, or your own trained people. Know what is being controlled, where the devices are and when the next visit is.
Anyone can say who the contractor is, when they last came and when they are next due. The matches the building.
The contract lapsed two owners ago, and the map shows bait stations in a wall that was knocked down.
Australia's Code requires practicable measures to keep pests out and eradicate them. says a professional is not a legal requirement in itself, but is needed if pests can't otherwise be controlled. Licensing rules for applying chemicals vary by place. Some law decides this for you. A Singapore food shop licence, including a caterer's, asks for a signed pest contract of 12 months or more with at least monthly inspection or treatment.