I always knew that there are free storage limits in Picasa, but there are some details I was not clear about, which might be useful for you as well.
While Picasa Web Albums offers 1 GB of free storage for photos and videos, all files under certain size limits don't count towards this free storage limit. This rule applies to all uploads for other Google product that store photos and videos in Picasa Web Albums as well, including Blogger, Google+ and Google Maps.
Note that photos up to 2048 x 2048 pixels and videos up to 15 minutes won't count towards your free storage.
Also, all photos uploaded in Google+ directly will be automatically resized to 2048 pixels (on their longest edge) and won't count towards your free storage quota.
All photos uploaded from the Picasa software or in Picasa Web Albums over the free size limit will not be automatically resized and will count towards your 1 GB of free storage. When you reach your storage limit, any new photos you upload larger than the free size limit will be automatically resized to 2048 pixels (on their longest edge).
The free storage sizes are good for sharing photos on the web, but if you prefer to upload your images at a larger size for better quality (archival or print), you can buy more storage at any time.