Our breakthrough with the "subscription" facility at PayPal has proved a bit hit, with members being able to renew membership with just a click.
And the best part is, when next year rolls around, PayPal automatically sends out the reminders. This saves valuable time for yanking out weeds and planting.
To use the online renewal you DO NOT have to have a PayPal account, though it is quicker if you do. You can use your credit card securely just like on other respected and secure sites.