Example, water intake report shortcode

add_shortcode( 'water_consumption', 'mycredpro_click_for_points' );
function mycredpro_click_for_points( $atts, $content = '' ) {

	extract( shortcode_atts( array(
		'ref'     => '',
		'message' => '',
		'hours'   => 2,
		'points'  => 10
	), $atts ) );

	// Must be logged in to see this shortcode
	if ( ! is_user_logged_in() ) return;

	// Get current time
	$now     = current_time( 'timestamp' );
	$user_id = get_current_user_id();

	// Get last entry
	$log = new myCRED_Query_Log( array(
		'user_id' => $user_id,
		'ref'     => $ref,
		'number'  => 1
	) );

	// User has an entry
	if ( $log->have_entries() ) {

		$last_entry = $log->results[0];

		// Make sure enough time has passed by removing x hours from the current time
		if ( $log_entry->time <= ( ( $hours * HOUR_IN_SECONDS ) - $now ) ) {

			// Intercept button clicks
			if ( isset( $_GET['water-intake'] ) && isset( $_GET['token'] ) && wp_verify_nonce( $_GET['token'], 'new-water-intake' ) ) {

				// User clicked on button, award points
				mycred_add(
					$ref,
					$user_id,
					$points,
					'Report of water intake'
				);

				// Show users a message showing they got points or something
				return '<p>' . $message . '</p>';

			}

			// Show the user the button they need to click on
			return '<a href="' . add_query_arg( array(
				'water-intake' => $now,
				'token'        => wp_create_token( 'new-water-intake' )
			) ) . '" class="btn btn-primary">Click to report water intake</a>';

		}

	}

	// Else just show somethig for users
	return '<p>' . $content . '</p>';

}