Okay, here's the deal. If you're going to be going on vacation, you've got 8 weeks to do it. This is because people have other countries they visit, and we must accomodate them if they have no internet. So the way this works is, MonBre has a system to delete all inactive people after 21 days of logout. The game actually sets their account to "inactive" after two weeks, in which their monsters will not age or anything, and then if still they are inactive, they are deleted. So, you're going on vacation? There's a very simple system that you have to go through to set yourself up for it.

In your account options, go to "vacation mode". Set how long you'll be gone (up to 5 weeks; come on people, I can't stress the server that much) and just don't log in. If you log in, you'll upset the vacation days and they'll be over. So in theory, you can be gone from the computer for 2 months, and only have to log in once between that period.