What is a Master Image?
The master image is the image used to generate the derivative image. So you can request as versions of the same master image you want.
Will I be charged by number of requests?
No. Requests are unlimited. Bandwidth too. It doesn't matter if you have 10 images with 1 million views each. Price won't change.
Is there a monthly minimum?
The minimum is $5.00 and it includes 4200 master images. After that, you get charged the regular rate, proportinally.
If I have 100k Master Images will I be charged by the same images every month?
No, only the images requested by your end-customer counts towards your usage. So what matters is how many images are still active on your end and not how many do you have in total.