Download latest version of WP Pro Membership add-on from your Dashboard → Purchases Tab. Install the downloaded file through plugin installation system. This is an add-on for Download Manager, so Download Manager plugin has to be installed and active to use WP Pro Membership.
Configure Cron for subscriptrion renewal reminder:
Add the following cron job in your hosting admin panel to run at a one-day interval:
https://yourdomain.com/?wppmsr=1
More details about setting up cron job:
Mastering Cron Jobs: A Comprehensive Guide to Creating Cron Jobs with cPanel and Plesk Parallel