The limited edition would have the purpose to allow the developer to build added values to Interworx or link his applications to Interworx without buying a licence or buy a hosting plan for just that purpose.
Just a suggestion, not really sure how that should be managed, maybe like Parallel does with Plesk which is free for one domain and 1 email.
Interworx did used do a Single Domain license, but it looks like it has been dropped now in favour of a 2 week unlimited license.
I see. Hummm, that won’t be confortable but yep installing a 2 week unlimited license each 2 weeks…argh that will be daunting and laborious 
but if it’s the only solution, it’s still the start of a happy face
Interworx Authorized resellers have access to VPS licenses (which aren’t available directly) so cost wise you could get a cheap Interworx VPS to develop against if you wished.
If you wanted something UK based, let me know
Thanks EveryGoodIdeas
I’ve just contacted you through your web site.