It seems that an account is now declared inactive after about 3 months of inactivity. If this happens, there is a chance that all units and colonies will be wiped during upcoming server downtimes. I would recommend that to keep your account active, that you log in at least once every 3 months if you want to preserve your units/facilities. Even more frequently would be better, say once every month. You do not need to log in for a long time...even a short duration of 5 minutes online should be enough. If you are no longer interested in playing, you can log in, hit Escape, and use the self destruct option listed on the window that appears. This will remove your units and colonies, reducing what would otherwise be inactive clutter on the server.