As many of you, I’ve been on a number of publishing sites, and will be probably be on many more.
I’ve learned a number of lessons.
Always do the work on your computer so you have a copy.
If it is published resave it with a ‘clue’ so that you know where you put it. When that site goes down, or doesn’t pay, or a new site comes along, you republish it and add another clue.
Be alert that some sites have/don’t have ‘plagiarism’ checkers. Often, when you republish all you have to do is change names/places and/or rearrange sentences.
In some cases you edit down to the minimum on other sites you have to add paragraphs.
Suppose you wrote the story of Goldilocks. Change her to Blondie, change the 3 Bears to 4 Zebras and and the porridge to baked beans.
There is or will be another site on the horizon. Prepare