Renew Subscription button in email

Hi there,

Would you be able to tell me if this is possible:

I would like to add a button in the reminder email that is sent to users when their subscription is about to expire.

I would like the button to automatically renew the (free) subscription that user is receiving the email about.

Background:
All subscriptions are free we use membership to protect the knowledge bases for our products. As a customer they are entitled to use the knowledge base. The subscriptions are all private and we force users onto the right subscription by providing a URL with the subscription encoded when they register.

They only reason they couldn't use the knowledge base is if they no longer worked for the company the purchases our product. If they still have access to their company email we presume they still work for that company so the can renew they subscription from the email.

Sorry for the story. Let me know if it doesn't make sense.

Thanks
Michael