Space travel in Prosperous Universe has two principal "costs": Time and fuel. Even a short hop from one planet to another of the same system, or to an orbital station in the same system, takes several hours. For flights between space systems, there is a STL (slower than light) component and a FTL (faster than light) component. The STL part is small if you for example fly from one orbital station to another one in another system; it gets big if you need to land on a planet. Because the FTL part is fast, as the name says, the time requirement between having to jump 1 system and having to jump several times isn't going up enormously. You can set the fuel consumption of both the STL and the FTL part. Using more fuel gets you to your destination faster. But quite often I set the FTL fuel usage to minimum, and the STL fuel usage to a bit over minimum, because the cost of flying faster goes up a lot quicker than the time goes down.

Because it takes a day or so to get from one commodity exchange to another, and it costs fuel, it is possible that goods have different prices in different markets. And you could, if you were so inclined, play Prosperous Universe exclusively as a trader. Just sell the materials you are given at the start to build a base and use the capital to buy cheap and sell high. Of course, if you buy a good and ship it, by the time your ship arrives, the price at the destination might already have changed.

Because of the fuel cost, it is recommended that new players choose a planet in a system with an orbital station / commodity exchange. The obvious disadvantage is that all the planets in those systems are very crowded. So I took a calculated gamble and chose a planet 5 jumps from the nearest station. Which means that at low fuel usage it takes me a day and a half to get from my base to the commodity exchange one way, and it costs me 2k currency each way for the fuel. As my starting base only makes about 2k a day profit, I won't be shipping my goods to market all that often.

One of the two advantages that a subscription has (this is very much not a Pay2Win game) is the access to so-called local markets. Which means that the rations I make I can sell directly on my planet to people who have a base without food production there. Or I can take a shipping contract to carry cargo for a fee from my planet to the station, and if that cargo doesn't take up all of my hold and the offered fee covers the fuel cost, I can piggyback my goods transports with that.

So why did the devs make access to shipping contracts only for subscribers? Because Prosperous Universe has absolutely no combat, but it does have "pirates". Well, I'd rather just call them thieves. "Pirates" in Prosperous Universe are people who picked up a shipping contract and never deliver it. If the player who posted the shipping contract doesn't prolong it repeatedly, the contract lapses at some point, and the "pirate" gets to keep both the shipping fee (if paid in advance) and the cargo. It is easy to see why you would want to have that feature behind a paywall.