Upgrade to premium now.

All plans include unlimited photo storage.

Here's what you get:

Unlimited photo uploads and storage.
Unlimited photo album capacity.
Safe storage for your albums that ensures they will never be lost or deleted.
Easy cancellation.

Does the upgrade apply to the entire account?

Yes, the premium membership applies to the entire account. Upgraded accounts will always have full access to their albums and photos — with absolutely no uploading restrictions.

If I have a premium membership and I set up an album and invite others to contribute to it, do these contributors also need a premium membership?

No, your friends and other contributors will have full access to the albums that you invite them to and can upload an unlimited number of photos.