Flickr's free account can only display 200 of your most recent photos at any one time. If you have more than 200 photos, the older photos won't be deleted but can't be viewed.

adrian yes I'm sure about it. Plus there's monthly bandwidth limit for uploads, about 100MB per month I think for the free accounts. Plus you can't upload some of your full size photos to your free account. Flickr will force you to resize it first or resize it for you.