Step 1:
Download any version of whmcs v9.x, for example:
or
(if you are using whmcs then skip step 1)

Step 2:
Access the file manager. Go to directory: public_html/vendor/whmcs/whmcs-foundation/lib

Step 3:
Proceed to delete the old License.php file. and unpack the License file, rename it to License.php upload to public_html/vendor/whmcs/whmcs-foundation/lib