RayMarine Plotter update

[n5ama]

I just purchased a boat that has a RayMarine Dragonfly 7 Pro plotter. The memory card on it is possibly out of date. I'll be using the boat in the western Gulf of Mexico mostly day sailing with a few overnight trips. The card appears to have current chart info at the boat's present location.

There was some information with the plotter that gave card update instructions from "Navionics" and it appears to be some sort of chart subscription update service. It appears that one can download updates with a $150 annual subscription. Is this the only way to get the latest chart information into this RayMarine plotter?

I'm not real sure the coastal charts have changed a whole lot unless you are sailing real close to the beach and I know there are some changes in tidal channels like for instance Timbalier Island in Louisiana that occur over a matter of days. I can't see how card update can keep track of the very near coastal areas and I'm not concerned with those changes anyway.

Any help defining my options here greatly appreciated.

Thanks