As for app.fiduswriter.org - it's a server that only costs us money and that we don't earn anything on. When we started it, it was just meant as a testing ground. Fidus Writer wasn't really stable enough to be used continuously, so we could not charge for it either. We wanted to avoid that people would tell us that they were about to lose their PhD thesis unless we rolled back an update and four a corresponding data backup because that would just mean even more time and money spent on that server. So we added a note when people sign up saying that we may delete all data at any time.
What then happened was that some people decided to ignore the notice and started writing really important papers anyway and so we ended up having to add backup solutions anyway. This is not really a service we offer, and it does mean extra work for us but in some cases it has worked out with us getting extra bug reports in from some who really use the app page a lot.
So no, we don't have a policy of deleting data on purpose, and we do all we can to do upgrades in ways that preserve the data there. Should we shut it down, we will at least out a warning to everyone about it and give you some time to download your data.
At least until the end of the year the server should continue as is. Eventually we will need to make it pay for itself in some way. When that happens, it will be announced and all current acount holders will be warned some weeks in advance.