Is the cart capable of selling subscriptions? I can't quite see how so does anyone have any suggestions? Or what they have done to sell a subscription?

I think you might be referring to recurring billing and there is no feature in the cart for that.
However, you could sell it through the website and use Paypal to setup the recurring billing.
Each month Paypal will send the invoice and alert you via email it has been sent, and you will get an email when they have paid.

That's about the only way I can think of handling it.

Thanks,
David

That's what I figured. Thanks.