Maybe it will be more clear like this:
Someone is registering whith this plan
1-He'll pay an entrance fee of 100 € (example) to subscribe.
2-NOTE :My website is going to be a place market, so he may sell stuffs that he's got into his shared VirtueMart Shop.
3-First time a customer buy him a one of his product, there's a 10(example) € subscription plan that starts for the current month, and so on : each month 10 € /month subscription plan that never(hopefully
) ends...
Thanks !