I think you can do it by running from master and explicitly specifying the actual db name in the query:
use master
select *
FROM your_db_name.dbo.Registos r
CROSS APPLY your_db_name.dbo.fnObtemCategoriaAviacao(r.PaisOrigem, r.PaisDestino)
SQL DBA,SQL Server MVP(07, 08, 09) "It's a dog-eat-dog world, and I'm wearing Milk-Bone underwear." "Norm", on "Cheers". Also from "Cheers", from "Carla": "You need to know 3 things about Tortelli men: Tortelli men draw women like flies; Tortelli men treat women like flies; Tortelli men's brains are in their flies".