Three facility claims appear on the page: Made in USA, an FDA-registered facility and GMP certified. They read like facts that anyone could check.
FDA registration means a food facility has registered with the agency. It is not an inspection result or an approval of a product. GMP refers to Good Manufacturing Practice rules that supplement makers must follow, and 'certified' normally implies a certificate from a named auditor.
The page names no certifier, facility or registration number that we could look up.
Ask the seller which organization issued the GMP certification and for a copy of the current certificate, and where the product is made. Be reasonable about it, since some of this may be confidential. A refusal to give any detail is itself useful to know before you spend $158 to $294.