private function get_api_versions() {

		$cache_key      = $this->product->get_key() . '_' . preg_replace( '/[^0-9a-zA-Z ]/m', '', $this->product->get_version() ) . 'versions';
		$cache_versions = get_transient( $cache_key );
		if ( false === $cache_versions ) {
			$versions = $this->get_remote_versions();
			set_transient( $cache_key, $versions, 5 * DAY_IN_SECONDS );
		} else {
			$versions = is_array( $cache_versions ) ? $cache_versions : array();
		}

		return $versions;
	}