If I am an owner of a site, I can place restrictions on its usage even if the site software is licensed under an open source license such as GPL or AGPL, right? Which law allows me to place such restrictions? For example, I can disallow uploading porn to my site, right? I can forbid circumventing site payment system, such as by distributing site passwords to other users or by modifying (I think, it's called "hacking") the site scripts, right?
Do I have similar rights for an open source smart contract created and uploaded to public servers by me? Can I legally disallow certain usages of smart contract (such as retrieving data from it directly to download a paid file for free bypassing my user interface software)?
Note that I realize I have no rights to restrict usage of my source code of a smart contract, because it is open source. I ask about a particular instance of smart contract running (similarly to a particular site running on a particular domain not to its underlying open source software).
Smart contract is a computer program that runs on servers (you can assume they are third-party servers) with the purpose to controls possible actions (such as money transfers) and disallow certain kinds of actions (like uncompensated money transfers).
I suspect it is something related to "terms of service". Can I apply terms of service to a running instance of a smart contact? I think, the main question is whether I am considered a service provider for the services provided by a smart contract: I spin it once and then the smart contract runs without my intervention (it is even not possible for me to stop my smart contract running, but I can for example change the amount of the monetary fee for its usage) on third-party servers.
There is a thing (securing a public file) that I cannot restrict with logic of a smart contact. So I am seeking a legal ("if you violate, I can sue") way to disallow these actions.