When a domain expires without being renewed, it is not lost at once. It goes through stages that give you a chance to get it back before it is released.
The stages in order
First the domain enters a grace period, when it can still be renewed as usual. Then comes a redemption period, which costs more and has more steps. After that it is released and anyone can register it.
What to do
- Renew right away if the domain is in its grace period.
- Contact support quickly during the redemption period.
- Expect connected services to stop while the domain has expired.
- Prevention is always better, so renew early.