Recently I learned that a local store pays for music. The music is part of the payment system and the payment processor. It's all included.
Here is an example of someone implemnting GNU payment.
https://www.reddit.com/r/technology/comments/4mnkin/gnu_taler_000_is_a_free_software_electronic/?st=iuzlzlz1&sh=7beb941e
There is also the unfolding of blockchain payment methods.
Perhaps Wikiloops music could be included with the wider universe of GNU software implementations. . .
Here is an example of someone implemnting GNU payment.
https://www.reddit.com/r/technology/comments/4mnkin/gnu_taler_000_is_a_free_software_electronic/?st=iuzlzlz1&sh=7beb941e
There is also the unfolding of blockchain payment methods.
Perhaps Wikiloops music could be included with the wider universe of GNU software implementations. . .