The Danish .dk domains have a nice feature, if you don't pay then they aren't freed right away, they are "quarantined" for a few months. In this period you're the only one who can renew it.
I believe all mainstream TLDs have this feature. In the past it used to be a nonissue when you renewed the domain in the grace period. Nowadays you just pay more but it still works.
Don't do it with a very desirable domain name though. The registrar might decide to grab it for themselves.
That's a useful feature; It's not impossible to be a little behind with renewal, particularly when it has to be done so often, a bit of a grace period for something so important should be a requirement.
