The former Chelsea and Real Madrid winger signed a partnership with the Easygo-owned business last week, which initially raised eyebrows as Stake is not licensed in Belgium.
The KSC is set to keep a close eye on how the deal unfolds, as advertising illegal gambling services to people in Belgium is banned.
If the advertising campaign is deemed to be targeting a Belgian audience, Hazard could face legal prosecution, including an administrative fine which could potentially be as much as €700,000 (£605,000)
“We are going to investigate to what extent that advertising is targeted at people in Belgium, because that is of course prohibited,” Stefaan Savenberg, a KSC spokesperson, confirmed to Belgian news outlet VTM NIEUWS.
“Mr Hazard has many Belgian followers on his Instagram pag..