一、以下链接为 官方下载 可以自行进行改版本号进行下载
版本号查看 https://download.whmcs.com/

下载
V8.8.0 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.8.0-release.1.zip
V8.7.3 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.7.3-release.1.zip
V8.6.2 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.6.2-release.1.zip
V8.6.1 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.6.1-release.1.zip
V8.5.1 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.5.1-release.1.zip
V8.4.1 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.4.1-release.1.zip
V8.3.2 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.3.2-release.1.zip
V8.2.1 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.2.1-release.1.zip
V8.1.3 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.1.3-release.1.zip
V8.1.2 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.1.2-release.1.zip
V8.1.1 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-8.1.1-release.1.zip
V7.10.3 https://s3.amazonaws.com/releases.whmcs.com/v2/pkgs/whmcs-7.10.3-release.1.zip

其他版本 下载 以此类推

二、替换授权文件（License.php） 进行开心

路径为 \vendor\whmcs\whmcs-foundation\lib\
开心文件下载 （License.php）

网上很多，谷歌一下……

替换之后正常安装就行 输入授权码的时候随便填