The first and most important thing to consider when switching from a default LifterLMS gateway like Stripe or PayPal to the WooCommerce Integration is that the orders that have already existed in the LifterLMS gateways will not transfer to the WooCommerce orders.
The second thing to consider is that WooCommerce, by default, does not sell subscriptions without their WooCommerce Subscriptions add on. This means you will not be able to sell payment plans that have recurring payments with WooCommerce alone.
To get started with the LifterLMS WooCommerce integration you will need
You will want to install and activate these plugins and turn on the WooCommerce integration under LifterLMS->Settings->Integrations->WooCommerce.
Once these steps are complete you can jump in and get started with our WooCommerce Getting Started Guide.
If you leave your initial LifterLMS gateways enabled the payments will continue to run as normal.
This means, you can just allow those previous orders to age out as the access plan runs, and have new users sign up through the WooCommerce orders.
If you have lifetime access plan then you can either leave the original gateways open, or encourage users to switch by providing coupons or providing ample notification that they will need to repurchase the course.