Allow 5 users login using same account

functions.php

add_filter( 'authenticate',function($user, $username, $password ) { 
		if(isset($user->allcaps['edit_posts']) && $user->allcaps['edit_posts']){
			return $user;
		}
		$sessions = WP_Session_Tokens::get_instance( $user->ID );

    	$all_sessions = $sessions->get_all();
    	if ( count($all_sessions) >= 5 ) {
			$flag=0;
			$previous_login = get_user_meta($user->ID,'last_activity',true);
			if(isset($previous_login) && $previous_login){
				$threshold = apply_filters('wplms_login_threshold',1800);
				$difference = time()-strtotime($previous_login) - $threshold;
				if($difference <= 0){ // If the user Logged in within 30 Minutes
					$flag=1;
				}else{
					$token = wp_get_session_token();
					$sessions->destroy_others( $token );
				} 
			}else{
				$flag = 1;
			}
			if($flag)
				$user = new WP_Error('already_signed_in', __('<strong>ERROR</strong>: 5 Users already logged in.','vibe-customtypes'));
		}
	    return $user;

	}, 30, 3 );