If you entered a wrong value into the allowed IP list then LAM might lock you out of the system. You can reset the IP list like this.
You need to manually edit the main configuration file (config.cfg) on the file system.
Locate config.cfg: On DEB/RPM installations it is in /usr/share/ldap-account-manager/config and for tar.bz2 in config folder.
Locate the "allowedHosts" entry in the file
Remove the line starting with "allowedHosts: "
Now you can edit the IP list again via LAM GUI.
Use a database admin tool (e.g. MySQL Workbench/phpMyAdmin) and connect to your database. Locate the table "main_configuration" and the row with value "config" in column "name". You will now need to edit this value which is in JSON format.
There is an entry "allowedHosts" followed by a colon. Now, remove anything of the value in quotes that comes directly after. Do not remove the quotes.
Now you can edit the IP list again via LAM GUI.