New Photos app on my iMac.

After my last OS X Yosemite 10.10.3 software update, my iPhoto app was replaced by the new "Photos" app. While merging my iPhoto library, it asked if I wanted to turn on Photos on iCloud, which will put my entire photo library on the iCloud. My question, if I enable Photos on iCloud do I have to purchase more cloud storage?

Thank you.