Migrating customer from one subscription to another

My site is:
https://www.slideheroes.com
I provide online video-based presentation writing training. I provide an online course, and am using the WPMU Membership plugin to protect content on my site. I am using WooCommerce to power the ecommerce transaction component.

I have a Free Trial which customers can sign-up for. When they do, they are subscribed to a WPMU subscription 'Free Trial', which gives them limited access to the site.

When a Free Trial user buys the course and becomes a full customer, how do I move them out of the 'Free Trial' subscription and into a new 'Full Access' level?

I have done a bit of digging. Is there a way for me to automatically move the customer from the Free Trial subscription to full access? Is this functionality that the WPMU Membership plugin provides? If so, how do I do that.

Mike