Just booked a flight on Air Canada. Once I had paid for the ticket, I was given the opportunity to select my seat, which included this upsell...
1. Just because something is (or was) "free" doesn't mean it's not worth paying for.
I'm 6'3". The comfort that comes from having a little extra leg room is worth $20 to me and I'm happy to pay it. In fact, I'd rather have the option of paying for it than getting it for free, since $20 takes a lot of my competition for the seat out of the running and gives me a better opportunity to actually get it.
"Competition" in this case is the 5' lady who booked two months ago. She'd probably take the seat for free, because extra room is always nice, but it's not worth $20 to her.
So everybody is happy... I get more leg room, the 5' lady gets her needs met, and Air Canada makes more money.
2. It's money on the table.
The downside for airlines is that airplane exit rows are required by law. Air Canada, like other airlines, has no choice whether to have them or not. The cost cannot be eliminated.
The upside is that people actually like sitting in an exit row.
So why not charge people for the privilege?
If you've got something for sale in limited quantity, even if it's something you've been giving away for free, charging something for it will not only benefit you, it may also benefit your customers.
You've also got fixed costs of running your music business, like recording costs, that could be offset by allowing people to participate in them. Music Producers Institute is a great example of this.
I encourage you to look at what you currently consider "free" to see it charging for it might actually be a benefit to you and your customers. In addition, take a look at fixed costs within your business, because many of them can be offset through options such as what Air Canada is doing with seats in exit rows.