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The term is "instrumental".

(music) Pertaining to, made by, or prepared for, an instrument, especially a musical instrument; as, instrumental music, distinguished from vocal music.

From wikipedia,

An instrumental is a musical composition or recording without lyrics or singing, although it might include some non-articulate vocal input; the music is primarily or exclusively produced by musical instruments.

However, it doesn't fit well grammatically in your example sentence, which is understandable. One "sings a song" but one would not say he or she "plays an instrumental", unless it was somehow important that you distinguish the fact that you're excluding voice.

Musicians would more likely not make the distinction that the piece has vocals or not, and say:

• I am playing a song. (informal use of the word "song" includes any musical piece)
• I am playing a piece. (mostly used for classical)
• I am playing a tune. (mostly used for jazz and pop)
• I am playing a number. (mostly used for jazz)

I would simply use the term non-expiring. For example, in Washington state, one can obtain a non-expiring license for child care.

You may also encounter the phrase valid in perpetuity, e.g. Hawaii Rev. Stat. §481B-13 (about electronic gift cards/certificates):

…if the gift certificate does not have an expiration date, it shall be valid in perpetuity.

This phrase is generally used in describing the length of effect of a legal document (like a contract or a constitution) or financial instrument rather than an identification, though, so I would consider it a secondary choice.