I'm not totally sure about that, I'm a bit new to this. Most places seem to require that you seed for long enough to make the torrent pretty much self sustaining, i.e. enough seeds and peers for it not to matter if you're there or not. One thing that you might like to look at is seedboxes, they can do the seeding for you, even if you're not there. I found a couple of free ones the other day sonicbit and seedr might do for you, if your demands aren't too huge.
Thank you very much for sharing that advice @sukebedave you're off to a great start with us here at Glo'
Yes you are correct that us and most other sites require the torrent to be seeded until it has enough seeds, without seeds the torrent dies,
if later on the seeds run out and you can't reseed it's preferred if you delete them,
if not generally they stay
(this only applies if it has been seeded long enough, if it's not then it gets deleted by us and that adds a bad mark next to your name and reputation - we do understand accidents and mistakes do happen and try to be fair with our decisions).