Add possibility to buy course again for logged-in users after access has expired

[harlembyte]

Is your feature request related to a problem? Please describe

When a user buys a course with time limited access, then after that time has ended, there is no way for them to re-enroll through the course page. The "Buy course" button stays hidden. This is because technically the student is still enrolled.

This is a flaw in the system for which at the moment the only solution is to manually unenroll all students with expired access.

Describe the solution you'd like

There could be two solutions. From my point of view best would be a slight re-design of the "Buy course" button, so that it also shows when the course is owned, and when access has expired.

Describe alternatives you've considered

The other solution would be an option to automatically end the enrollment for all students whose access has ended.

[donnapep]

Copied from https://github.com/Automattic/sensei-pro/issues/2670.

Is your feature request related to a problem? Please describe

Currently, when a student's course access expires (e.g., after 30, 90, or 365 days), they remain technically enrolled in the course but cannot access the content. This creates several problems:

The "Buy" button doesn't reappear on the course page because Sensei still considers them enrolled, preventing self-service renewal
Manual unenrollment is required for each expired student before they can repurchase, which becomes unmanageable with many students
Poor user experience - students can't easily renew their access and need to contact support
No clear "expired" status - there's no distinction between active enrolled and expired enrolled states
Administrative burden - constantly monitoring and manually managing expired enrollments is time-consuming

Describe the solution you'd like

Automatic unenrollment option:

Add a course setting: "Automatically unenroll students when access expires"
When enabled, students are removed from the course when their time limit is reached
This would make the "Buy" button automatically reappear
"Expired" enrollment status:

Dedicated "Renew" button/link for expired students
Option to offer discounted renewal pricing
Preserve course progress when renewing

Describe alternatives you've considered

WooCommerce Subscriptions - Not suitable as the user doesn't want recurring payments; they prefer one-time purchases with defined access periods

Additional context

Should work with both WooCommerce and Sensei's built-in payment methods
Need to preserve course progress data even after unenrollment
Must handle edge cases (partially completed courses, certificates already issued, etc.)