What HTML is available to modify is a part of the CBSubs template files below.
components/com_comprofiler/plugin/user/plug_cbpaidsubscriptions/templates/
I do not recommend modifying the default template, but instead making a new installable template from it that you can modify. If you modify the default your changes will be lost on upgrade. Alternatively you can restyle it using entirely CSS and place your custom CSS in a template override plugin or in your Joomla template CSS files.