Answer:
reciprocity principle
Step-by-step explanation:
A reciprocity principle is a form of socio-psychological principle in which individuals generally tend to pay back in good, and in any form of capacity for whatever favor they receive.
Hence, in this case, the music company is hoping the the "reciprocity principle" will work on consumers that subscribe to free music as they might wish to give back to the company based on consumers feeling indebted to them for all the free music that was streamed