"If an employee is charged for working without a valid licence, the agency they work for may also face charges."

https://www.ontario.ca/page/requirements-security-guard-and-private-investigator-agencies#:~:text=To%20work%20as%20a%20security,be%20verified%20online%20through%20ServiceOntario.

"Security guards and private investigators are responsible for getting their own licences and renewing them before they expire."

The license expires every year. It would make sense that the guard or employee would also get the background check for dealing with vulnerable people as it expires yearly too. This is not the "sector,"RCMP," "truck driver," etc. check as these aren't thorough.