During my time in SL, I've come across several talented creators who maintain systems or games that periodically communicate with a server either in-world, or externally, to verify whether a user has permission to use the product.
In many cases, these systems are sold for an upfront fee.
The issue is that when someone pays for an asset that relies on ongoing server-side authorization, their ability to use that asset ultimately remains at the creator's discretion. This can create significant problems for customers, as access can be revoked at any time if the creator decides to ban them or discontinue authorization. I don't believe this is acceptable unless it is clearly disclosed before purchase.
I propose the following:
Any item that communicates with a server (whether in-world or external) for authorization, licensing, or functionality purposes should be required to disclose this fact. The listing/advertisement should also explicitly warn users that the creator may terminate their access to the product at any time.
I should clarify that this would be items that are sold FOR PROFIT, and not for free (as the loss is then not material).
This allows buyers to make informed purchasing decisions and better understand the risks associated with server-dependent products, rather than using it and ending up paying for something that they could lose access to over anything the creator sees fit.