Hello Phill Hodgkinson,
Thanks for contacting us.
You can purchase the license under any name or any company, but the domain on the license must match the top level domain on the website. Based on your input, I would recommend having your client purchase the license. Then, assign you as a licensed developer. This way, you can download the license and submit tickets, while they have actual ownership and can add or remove developers. To assign you as a developer, have your client login to their user account. Then, click on Licensed Developers, which is under Your Licenses, in the middle of the screen on the My Account page.
Kindly let us know if you have any questions.
the Telerik team