So i cant find anything about the activpub implementation they use on pixelfed except this discussion i would assume they used the peertube implementation (someone please lmk) which is simply this
"licence":{"identifier":"5",// Internal PeerTube ID"name":"Attribution - Non Commercial - Share Alike"},
Perhaps the fetiverse could come up with some way that we, as individuals, could profit from our own metadata. 
The first step in that would be allowing us to attach licences to our content same a pixelfed.
Yes… But how? I think the real first step would be devising a common format for that data.
So i cant find anything about the activpub implementation they use on pixelfed except this discussion i would assume they used the peertube implementation (someone please lmk) which is simply this
"licence":{ "identifier": "5", // Internal PeerTube ID "name": "Attribution - Non Commercial - Share Alike" },As a property of the content object on activpub.