You don't need to have your car serviced by Honda to maintain the manufacturer warranty. But the garage you use MUST use Honda approved parts and fluids. These should be detailed on an itemised invoice, otherwise, you have no proof the correct work has been carried out and you will risk invalidating the warranty.

It's also important to note that your car may miss out on important updates and software upgrades, which are usually applied during the annual service by the dealer. A car with a dealer stamped service history will also be more desirable than one without when it comes to selling.