PDFpen 2 for the iPhone and iPad is out, and the new version adds support for storing documents on iCloud Drive, adds an iOS 8 interface, and is now a Universal app for the iPhone, iPad, and iPod touch. PDFpen 2 is a PDF editor you can use when you're away from your computer, and the clever people at Smile figured out how to give its customers an upgrade price option even though that isn't something Apple supports through the App Store.
PDFpen 2 for the iPhone and iPad is out, and you can get upgrade pricing. Sort of.
If you already own PDFpen for the iPad, hence your desire to pay for an upgrade instead of full price, just buy Smile's PDFpen 2 Pack for iPad. It'll cost you US$7 instead of the $19.99 price for just PDFpen 2, and you get to keep your older version of PDFpen as well. If you're a PDFpen for iPhone user, the bundle will cost you $15, which isn't as much of a discount as iPad users get, bit it still saves a few dollars.
Those discounts assume you paid full price for the earlier product versions. If not, you'll pay more for the upgrade, but still less than full price.
The new version of PDFpen for iPhone and iPad requires iOS 8, and supports password protecting documents, AirDrop for document sharing, palm rejection when writing and highlighting, and more.
PDFpen 2 for the iPhone and iPad is also available as a stand-alone download from Apple's iTunes-based App Store for $19.99.