Given the volume cap of Apple and the formulas they can pop out stating "after three months of free use, x users will convert into paying users resulting in y r

Given the volume cap of Apple and the formulas they can pop out stating "after three months of free use, x users will convert into paying users resulting in y revenu and z profit for you" to record labels, all it boils down is record labels willing to believe Apple their predictions and whether they are happy with that y in return of 3 months of upfront payment.