I am reading comments on paid content and various markets in OpenSimulator. I would like to share my thoughts and ask you to correct me if I'm wrong and shed some light on the topic.
In my opinion, Kitely has the best system both as a market and a control system. After working with it for a while, they have managed to achieve a significant result. Creators can set content that they don't want to be forced into permissions as non-exportable to other OpenSim grids, thus protecting it from the infamous GOD mode that users across all grids now have. On the other hand, those who want to make their content exportable risk selling fewer copies since it may be forced and potentially distributed everywhere.
I find it very challenging for original OpenSim creators to sell products and come close to the earnings of Second Life. For instance, even if I sell a product as no-transfer, if it ends up in the grid of a user with GOD powers, it will certainly be unlocked. Unlocking content has become an instinctive practice for many users.
It's a different story for those who create original products and release them for free. Even if unlocked, they will not suffer excessive damage (I hope), and people will be more inclined to respect permissions (I hope) and invite others to get their copy directly from the original creator without forcing and redistributing it as a favor for various friends on other grids (doing it discreetly), which can happen with paid products.
I honestly don't believe this problem will be resolved as long as GOD mode is accessible to everyone. Some grids have denied GOD mode to enforce respect for original creators' content, but these are not popular among users who can get everything they want with GOD mode. They prefer, at the same cost, to obtain regions even in poorly performing grids that allow them to do anything.
Another problem is the backup copies of regions. There have been grids that did not allow the default backup of objects without sufficient permissions, but these grids had no luck or popularity. Meanwhile, those who do not apply such restrictions obviously have more success. Even reloading the OAR on a new grid, the original creator could be permanently lost, creating confusion about who the original creator of the product is and whether the object has been purchased or not.
Therefore, honestly, I think selling on more or less renowned grids is limited to one, two, or ten sales, the time it takes for the product to be unlocked, given away, or loaded into other grids via OAR. All of this, except for Kitely, which has an exceptional system for controlling the "products" leaving its platform, a system that they don't publicly share from what I understand.