As a result of registered partnership

Prerequisites for naturalization as a result of registered partnership
(§ 5 LGBl. 2008 No. 306)

The partner of a Liechtenstein citizen is admitted to the national citizenship upon application if:

he/she can prove a regular Liechtenstein residence of ten years prior to application, whereby the years after the registration of the partnership count double
he/she has lived in a registered partnership with a Liechtenstein citizen for at least five years
the Liechtenstein partner has not acquired Liechtenstein citizenship as a result of marriage or registered partnership
Waiver of the previous citizenship
Proof of sufficient knowledge of the German language
Proof of basic knowledge of the legal system and the state structure of Liechtenstein (Staatskundeprüfung)

Link Website: https://www.llv.li/en/individuals/migration-and-integration/wedding/as-a-result-of-registered-partnership