Cadbury is among 800 firms that will have to re-apply for a Royal Warrant as the prestigious label is now void, following the death of the Queen.
But according to the Royal Warrant Holders Association (RWHA), these warrants became void when the Queen died.
However, it adds "the company or individual may continue to use the Royal Arms in connection with the business for up to two years, provided there is no significant change within the company concerned".
The distinctive image of the royal coat of arms depicts the lion of England, unicorn of Scotland and a shield divided into four quarters followed by the words "by appointment to Her Majesty the Queen".
It features regularly on the branding of companies over 600 businesses like Twinings, Jaguar, Land Rover, Clarins and Fortnum and Mason, which may now have to change.
The distinctive coat of arms will have to be phased out of their products in the next 24 months.
Firms are eligible to apply for a Royal Warrant if they regularly supply products or services to the Royal Household, on an ongoing basis for five years out of the past seven.
Applicants also have to prove they are ethical and sustainable, by providing an environmental policy and action plan.
Heinz is also one of the iconic brands affected.
A spokeswoman said: "It's been our highest honour to supply The Royal Households with Heinz products since 1951, and we sincerely hope to be able to continue doing so for many years to come.
"However, at this time, our thoughts are with the members of the Royal Family."
Around 30 Royal Warrants are granted a year, and the same number are withdrawn.
The total number of Royal Warrants changes monthly, but there are approximately 875 Royal Warrants at any one time.
A Royal Warrant is usually granted for up to five years and reviewed in the year before it is due to expire.
Other brands granted warrants by the late Queen Elizabeth II include Gordon's, Coca-Cola, Pimm's, Premier Foods, and more.