A word or phrase to describe documents that can expire
Solution 1:
While I can find no authority to support these, the terms time-limited and time-restricted seem to logically (and semantically) apply.
If you want a colloquial phrase, consider good through (or thru) and good until as adjectival phrases.
Solution 2:
- Transient-lasting only for a short time, (temporary)
- Transitory-not permanent
- Temporary