Flckr has changed policy to only allow 1000 images of free storage. Beyond that you can join a $50 annual plan for unlimited storage. If you have an account with more than 1000 images Flickr will start deleting them starting this coming February.
https://9to5mac.com/2018/11/01/flickr-cuts-back-free-account-perks/
Another note on this. They’re offering a 30% discount for the “Pro” account as an enticement, but to get it you need to follow the link offering it. If you just go straight to the “plans” page they’ll talk about 30% off, but it’s just compared to the monthly plan. Bottom line is, if it says more than $35 at checkout, go back and try to find the discount link.