Why does Everalbum delete my photos?

I downloaded the Everalbum app on my Iphone 6 and I've been deleting pictures from my phone thinking they are safe in this app which is supposed to save your photos forever. After deleting a couple photos of me and my boyfriend I went to check if they were saved and they weren t and I was like maybe they re still not loaded yet so I waited a while. To confirm my pictures were being deleted, I took a random screnshot and waited for it to appear in my everalbum and after it did I deleted it off y phone. After deeting the screenshot, the everalbum age refreshed on its own and the screenshot was gone. IIm so confused on why it did that and now IIm worried about other pictures I feel are missing.

Any important information will be / should be copied to at least 2 other places. E.g. A cloud account and a standalone disk or memory stick.
If you haven't bothered to copy them and back them up, then by definition they are not important to you.