How do I switch to Focus Plus from another theme?

HubSpot does not migrate pages between themes, so switching from any other theme (or from the free Focus theme) works the same way: install Focus Plus from the Marketplace, then rebuild each page with a Focus Plus template and its modules. The text, images, forms, blog posts, CTAs and menus stay in your HubSpot account and can be reused; only the page layouts are built again.