Invitation and trial accounts feature

[Orb Tech]

We are currently using freeRADIUS module for selling VPN accounts. we need design of new or customising current features in WHMC to have the following option:

 

Invitations and trial accounts:

 

- Each customer can send [x] number of invitations to other emails.

- If the destination email accepts the invitations he get a free trial account

- The inviter gets reward that can be used towards free account or cash + He gets [x] new invitation allowance

 

-Invitation only mode: people from some countries can only purchase accounts if they are invited.

 

Please guide us on how this can be done, or how much it costs you to do this.