By law, all professionals in the hospitality sector must keep their guest registration book up-to-date.
The forms of entry parts of travelers will conform to the model established in the Annex of Order INT / 1922/2003, of July 3 and will be generated by the establishments themselves
The establishments may fill in the forms of Entry Parties by manual procedures or by computer procedures, but the traveler must sign this part inexcusably.
Once the form has been completed and signed, it will remain in the establishment for the purpose of making a book-record, ordered in a correlative manner and consisting of books or notebooks that will integrate a minimum of 100 pages and a maximum of 500.
The registry book of the establishment in question, constituted in accordance with the provisions of the preceding paragraph, will be available at all times to the members of the Security Forces with competence in the matter, and the establishments are obliged to exhibit it when to it they are required.
The establishments must keep the Books-registration for a period of three years, counting from the date of the last of the record sheets that comprise them.
In the following links are available the documents to be filled in by the guests in Spanish, English and German:
Guest registration sheet – Spanish
Guest registration sheet – English
Guest registration sheet – Deutsch
Sources:
https://hospederias.guardiacivil.es/
http://www.interior.gob.es/web/servicios-al-ciudadano/seguridad/libro-registro-de-viajeros/partes-de-entrada-y-libro-registro