How do trading charter items work?

[pemmons1]

These items come in weaker and stronger versions as to their lifespan and the trading advantage that should be gained when they are active.

I wondered earlier how to activate them. As I recall, you put the item in a ship socket and then click on it again. The background changes to a lighter color and gradually darkens again like tracing the movement of a clock hand, so that we can see how much time is left. Also, once activated it can't be deactivated or removed from the socket (at least not as easily).

But what do they do? I installed and activated an expensive, powerful "Royal trading charter" in my flag ship and started selling lots of fur coats to Madame Kahina. But the priceI got for them was the same as before. Disappointing. Does the charter apply only to what you buy, and not what you sell?

[Smokerbait]

Yes, I believe that is how they work. Their benefits are all in the negatives (ex. Trade Prices -15%) which really only benefit you when buying something.