Is this going to use part of the iCloud storage one buys? e.g. I have 25GB. Should I buy more if I have a lot of pictures?
Since it's unlikely that Apple would give everyone unlimited photo storage for free, it's safe to assume that YES iCloud Photo Library will count against your new iCloud Drive storage. AS far as whether or not you should upgrade to more storage, only you can answer that since we have no idea how many photos you have or how much storage they take up.
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