On this site Gold System Plugin is tested
Just be aware that this is just testing. My local enviroment is PHP 5.6 and this one use PHP 7.0. No money are needed for golds.
I am trying to learn more from the best plugin author I know (or I best understand it's code) and to get his code to work under new version.
I never used this plugin with 0.7 version and I really don't know from where I have source code - I just found it while cleaning my old 1.0.4 repository.