我正在Wordpress网站上为非营利组织工作。他们正在使用＆＃34;免费＆＃34; PaidMembershipsPro插件。他们已经使用了几年没有问题。但是，插件Updating Plugin Paid Memberships Pro - Sponsored Members Add On的最新更新将不适用。错误是：
You must have a valid PMPro Plus License Key to update PMPro Plus add ons. The following plugins will not be updated: Paid Memberships Pro - Sponsored Members Add On
The update process is starting. This process may take a while on some hosts, so please be patient.
Updating Plugin Paid Memberships Pro - Sponsored Members Add On (1/1)
Downloading update from http://license.paidmembershipspro.com/downloads/plus/pmpro-sponsored-members.zip…
Unpacking the update…
An error occurred while updating Paid Memberships Pro - Sponsored Members Add On: The package could not be installed. PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature
他们是否将其设为非免费插件？由于非营利组织使用的是免费版本，因此无法访问支持论坛以及我可以在网站上找到的有用信息。