Nah your account will be fine. Only thing might be if the server's data gets corrupted (happened a couple months ago), but otherwise your lists are safe.
Recommendation:
- Add tags to everything you're reading/want to read/already read, because it's less likely to be lost due to corruption.
- manually make a list of your lists here, so you can re-add them in case of data loss.
Long time logging out won't do anything (I've been here a while and never lost things automatically except for server data loss)

Guys if someone knows please tell me. Do u lose all ur list and read/already read if u log out for too long?? I have an exam in few weeks and was going to logout because I was getting Hella distracted but I'm scared I m going to lose all my lists etc?