A software license and a license key or serial number ("Software Product License"), issued only by ej-technologies or its authorized agents to a designated user may be required according to the following agreement.

软件许可证和许可证密钥或序列号（“软件产品许可证”），只能由EJ-技术或其授权代理人签发给指定的用户可以根据以下协议是必需的。

这里的 issue 应该是颁发的意思，用于修饰前面的许可证，我觉得是 which is issued 的省略，但这里加了个“，”是什么意思呢？表明这是个限制性定于成语且省略了 which is ?我的理解正确吗