It may be because I explained the idea poorly.
The idea is to offer a delayed action free trial along the lines of:
"Try membership for 14 days. If, during that time you decide you don't wish to become a full member, simply cancel your order and pay nothing. If you do decide to continue, you will pay just XXXX a year."
If we can choose the length of the free trial, say, 7 days, 14 days or 30 days that would suit most kinds of membership websites.
A delayed action free trial is a proven way to increase the number of sign-ups a website will achieve. Memberships shoot up! Most people want to try something out before they buy.
Thanks,
Peter