Unlock Key/ License that removes the ads and unlocks certain features from the free version of the F-Stop Media Gallery application here: http://www.amazon.com/gp/product/B008ZXAHDO

The free version must be installed with this app. It just checks to see that this key is installed and then removes the ads and unlocks certain features.

UNLOCKED FEATURES:

PLACES: Use the powerful and intuitive interface of Google Maps [1] to view your media on a map. Upgrading to PRO unlocks full access to browse, edit and share any of the media shown on the map.

SEARCH: Search results will return all the media that matches the search criteria instead of just 10 in the free version.

WRITE METADATA: Save your tags and ratings directly into your JPG images and/or write sidecar files for all other supported file types. We write the metadata using the XMP standard so it can be read by popular applications such as Adobe Lightroom, Apple Aperture, and Windows Live Photo Gallery.

CUSTOM SORTING: Use drag and drop to sort your media in any order you want.

CUSTOM NAVIGATION DRAWER: Hide and/or edit items in the side navigation drawer.

BOOKMARKS: Add unlimited bookmarks to the navigation drawer.

THEMES: Unlock all themes to make F-Stop look the way YOU want.

NESTED FOLDERS: Browse your media by the folder structure on your device. Very convenient if you organize your media by folders.

NESTED ALBUMS: Create albums inside of albums similar to nested folders but with albums.

SMART ALBUMS: Unlock all smart album conditions such as: Number of Tags, Orientation, Media Type, Extension, File Name, Size and any future additions.

START-UP SCREEN: This feature allows you to select the start-up screen. Options include Folders, Albums, Tags, Ratings, etc.

[1] Google Maps must be installed on the device

★ Note for Kit Kat users: Google has removed write permissions on the SD card for ALL third party apps. We do have a workaround we implemented in v3.1+, but it does not work on all devices including the S5 and some Xperia devices.
Here is some more info:
http://lifehacker.com/android-kitkat-blocks-some-access-to-micro-sd-cards-1524997895