I'm using V3.1.4, It was in a ticket where a IPB staff told me I could request this. He told me that this feature was not in any boards.
The only permissions I know of in my version are forum permissions and group permissions. There is clearly not a feature like this in any settings. I don't know if you fully read the first post because I haven't even seen this in the newest version.
The main purpose of this topic was to request a system that replaces links with: "You must be a member to view this link, please sign in or register" Something like that.