Generally, if an update does not contain any specific database changes, you can roll back (downgrade) to a previous version if necessary.
Rollback is best handled via FTP.
- Go to the plugin’s “advanced” page in the wordpress.org repository.
- At the bottom of that page, select the version you need to roll back to.
- In the WP plugin panel, deactivate WP-Members.
- Using FTP, delete the contents of the wp-members folder (/wp-content/plugins/wp-members).
- Unzip the roll back version locally.
- Using FTP, copy the roll back version to your site.
- Reactivate.
IMPORTANT: DO NOT run the “delete” option from the WordPress plugin panel when doing a rollback. That will delete all of your current plugin settings and require you to update your settings.