Capacity-based in something like Netflix. One could pay monthly for a virtual “box” of recordings, based on size of the box. Want more? Pay for a bigger box.

Generally, in this model, the ideal user would be someone geared towards hearing new things every month. But, unlike with Netflix DVDs, with a virtual box, there’d likely be plenty of (virtual) space for long term holding of favorites, etc.

Another comment about these kinds of models: they potentially leave more room to allow for sharing. E.g., in a capacity based system, people could trade music between each other’s virtual boxes, and the system would not have to monitor that, and still could easily figure out how much to charge everyone (simply: based on capacity).

A variant: you could throw bandwidth in there as well: e.g., 10 GB of storage and 5GB of trade between your friend, each a month.