Sef-hosted GitLab using GitLab CI

Hello! I’m new to CI, I have my own GitLab CE on a VPS since a few years. Now I’d like to use GitLab CI. I’ve read that after version 8 GitLab comes with CI included and enabled by default. I also read that is not recommended to have runners on the same server that GitLab. That confused me a bit.

My VPS is slow 1core and 1gb ram + 3gb swap. So I was thinking on using GitLab CI from GitLab web (also so runners are not same server as GitLab). Is that possible? Should I use it on my own VPS? Or how?

Thank-you very much!!