Gives 5 errors when you activate

I installed and activated, and immediately WP gives these errors at the top of every page.

Strict Standards: Declaration of Walker_PostExpirator_Category_Checklist::start_lvl() should be compatible with Walker::start_lvl(&$output, $depth = 0, $args = Array) in /home/abcco/public_html/wp/wp-content/plugins/post-expirator/post-expirator.php on line 1291

Strict Standards: Declaration of Walker_PostExpirator_Category_Checklist::end_lvl() should be compatible with Walker::end_lvl(&$output, $depth = 0, $args = Array) in /home/abcco/public_html/wp/wp-content/plugins/post-expirator/post-expirator.php on line 1291

Strict Standards: Declaration of Walker_PostExpirator_Category_Checklist::start_el() should be compatible with Walker::start_el(&$output, $object, $depth = 0, $args = Array, $current_object_id = 0) in /home/abcco/public_html/wp/wp-content/plugins/post-expirator/post-expirator.php on line 1291

Strict Standards: Declaration of Walker_PostExpirator_Category_Checklist::end_el() should be compatible with Walker::end_el(&$output, $object, $depth = 0, $args = Array) in /home/abcco/public_html/wp/wp-content/plugins/post-expirator/post-expirator.php on line 1291

Warning: session_start(): Cannot send session cache limiter – headers already sent (output started at /home/abcco/public_html/wp/wp-content/plugins/post-expirator/post-expirator.php:1291) in /home/abcco/public_html/wp/wp-content/plugins/wordpress-simple-paypal-shopping-cart/wp_shopping_cart.php on line 18

https://ww.wp.xz.cn/plugins/event-registration/