Category permission disables when server restarts

For example, when someone gets top 1 in a category, a group is created in the permissions. I give permission for the player who has top 1 heli kills to have permission to use an attack heli through the spawn heli plugin. It works perfectly! However, when the server is restarted, the permission to the spawn heli plugin is disabled and I need to enable it every time I restart my server. Does anyone know how I can persistently maintain permissions in the 'helikills' group (or any other)?
NOTE: I use the 'permissions manager' plugin.

Thanks for replying! No, is set to false. 

As I see, the holders stay on the groups with top 1 categories. But, the permissions on spawn heli plugin don't maintain the config. So, in fact, don't destroy groups on unload (restart the server), but, after restart the server, the config on spawn heli plugin don't maintain...

Yes, I understand that when #1 loses the title he is removed from the group. However, the same person was in the group with the heli spawn plugin config to spawn heli enabled. When the server restarts, he remains in the group, in fact, but the heli spawn config is disabled to the default (no config enabled, such as spawning a heli). On my server, whoever wins the 'heliKills' category title gains access to spawn a mini heli. However, every time the server restarts, this config is disabled for the owner of the 'heliKills' group and I need to reable the spawn mini heli again, every time the server restart