A domain is not bought outright; it is registered for a period of years and renewed. The registrant is the party that holds that registration and is bound by the registration agreement. It is worth checking that the registrant on record is you or your company, and not an agency, a former employee or a web designer, because in a dispute the record is what counts.
The registrant must keep contact details accurate, and for gTLDs the registrar verifies the email address or phone number; a domain can be suspended when verification fails. Older records also list administrative and technical contacts, which many registries have since dropped.
In public WHOIS and RDAP output the registrant's personal data is usually redacted or replaced by a privacy service. OrbitProbe shows at most the registrant organisation and country, and never treats that as proof of who controls a domain.