CSF/LFD: Firewall automatically disabling again and again

I have setup a droplet on Digital Ocean, and installed CentOS Web Panel. After the initial configuration, I've enabled CSF/LFD firewall. But it is automatically disabling, again and again. I have enabled 3 time in last 24 hours.

I want to know: where can I find error log OR how do I trace why it's disabling and fix it?

Update: I found from logs that only lfd daemon is stopping with this error message in logs Unable to fork: Cannot allocate memory. I've upgraded droplet from 1 GB to 2 GB ram droplet, but it is still happening.

I am pretty sure, there is some bug or any other problem because it is suppose to work on 1 GB server.

Please somebody help...