Hi Ricardo
Normally, you will just need to upload the file pt-BR.com_osmembership.ini in the zip file to language/pt-BR folder and it should be fine
If it still does not work like that, submit a support ticket sending us super admin account of your site so that we can check it for you
Also, beside translating language, you need to translate custom field title and the email messages as well. See
membershipprodoc.joomservices.com/basic-...one-english-language for detailed instructions
Tuan