Is there an English Proficiency Test with lifetime validity?

If you obtain a degree from a country where English is the official language, then nobody will ask you for English proficiency tests in later applications. This is especially the case if you are applying for a postgraduate degree in North America or Europe.

I am not answering to the visa part of your question, however, as for educational purposes; the Cambridge tests are the ones which do not have any expiry date. IELTS and BULATS are exceptions in their system. The score you obtain shows your skills at the time you sit the exam. This link has valuable information on your question (link +)

However, even if you have those scores, some institutions may require the candidates to bring results no older than two years in order to be sure about the language skills of the candidates. Some other institutes may accept older scores if they see proof of studying or maintaining language skills, such as participating in classes, working in English speaking environments, receiving supporting letter from the employer indicating that the candidate has worked on English demanding projects, etc.

If you have doubt about which language test to sit, you would better to consult the institute to which you are applying.

Unfortunately no English test can claim lifetime validity. If one doesn't use a language, one's proficiency with it will go down over time. Two years is the limit IELTS and TOEFL use; beyond that, you need to demonstrate you still know the language well.

It's annoying because some people (like me) use English as their main language although they didn't grow up in an English-dominant country, and they still have to demonstrate that they know English well again and again, but c'est la vie.