This response by Jason Fried to Apple on why they don't want to use In App Purchase is pure gold. He's 100% spot on, and anyone that has run a subscription business knows these truths well. 

When Apple forces companies to offer In App Purchases in order to be on their platform, they also dictate the limits to which you can help your customer. This has a detrimental impact on the customer experience, and your relationship with your customer. It can flat out ruin an interaction, damage your reputation, and it can literally cost you customers. It prevents us from providing exceptional customer service when someone who uses our product needs help.

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For example, at Basecamp we help people for all sorts of reasons. We apply credit to accounts for all sorts of reasons. We provide hardship exceptions for all sorts of reasons. We discount our software for teachers. We provide free versions for first responders. We extend trials for those who need more time. We extend payment terms occasionally for those who can't make ends meet this month. We make exceptions because people are exceptional. We take enormous pride in helping people out. And we're damn good at it.

If we had to push our customers through Apple's system, we couldn't do any of that. Apple's rules prevent us from servicing our customers, yet Apple gives us no choice but to submit to those onerous rules or not be represented on their platform. That's flat out hostile - to us, to our customers, and to the community.

The whole piece is wonderful.