You can now hide models and pages from non subscribers. Using this technique you can set up bonus memberships for your other sites at Shopmaker.
Create a cheap payment plan at site A, usable with promotion code only.
Create a page at site B, linking the promotion code payment plan from site A. Hide this page from non subscribers
As soon as a client subscribes to site B, the page is visible for him and he may subscribe to site B for a cheaper price.
You now have a statistic of cancellation reasons for your clients at your sales statistics.
For merchants using the gamma template: You can now add an adult confirmation dialog to your site that is shown to clients prior entering the site. See an example here.