What licensing system/module does scrapebox use(developer pov)?

[DreamBigWorkHard]

A robust licensing system/module is needed especially for Internet Marketing tools/applications, and after checking out lots of them I found that scrapebox's solution is simple yet powerful enough.

So I was wondering, what licensing system/module do they use? Or maybe they actually wrote it themself?

 

[innozemec]

It looks to me like a custom written, though i haven't inspected it in details..

 

[DreamBigWorkHard]

It looks to me like a custom written, though i haven't inspected it in details..

If it's custom written, is there some kind of C/S model or structure to follow?