[durana]

I've never priced a product or service myself, but thinking about the roll over credit model from the consumer perspective I see a potential problem. If a subscriber's usage never exceeds the monthly minimum, then that subscriber is going to roll over credits every month and accumulate credits they will never use. The value of those rolled over credits that will never be used will highlight to the subscriber how much money they have paid for credits they didn't use. No one likes to know they are wasting money by paying for more than they need.

I don't know what your service is, so I can't reason about how subscribers would use it from month to month, but I would think you could control the amount of roll over credits accumulated by setting the monthly minimum low enough that most subscribers go over it and use accumulated credits.

[thefool]

This is a great point. Without some sort of expiration system, keeping credits will probably convince the person to ultimately drop the service.

[paulhart]

Agreed, this is my "cynical customer" perspective, the "breaking point" I alluded to above.