Since the Bookeo widget's content comes from the bookeo.com domain (even when you use the widget), any keyword contained in the widget does not count towards the SEO of your own domain.
You can, however, list the content of the widget - for example a description of your services - in a page of your website, and place a Book Now button or the widget, pointing to the specific service, in that page. You can find direct booking buttons and links in Marketing>Booking button and links.