All of a sudden needs password to remote

Hello,

I set up my home and work computers a couple of weeks ago to accept remote control without a password. It worked perfectly until today when I tried to access my home computer it asked for a password. Unfortunately I couldn't remember the password and it wouldn't let me in.

Thankfully someone was home and they were able to accept my incoming remote request but I can't always count on this being the case.

How could it have lost the permission to auto connect a remote session without password?

Thanks for your help.

PS I'm using Macs