Cleaning Tape Expired date

This question is better asked of the manufacturer of your cleaning tapes.  In general, the answer is usually more a factor of number of uses of the tape than of any particular time period.

As suggested by Chris, the exact information is available with manufacturer and it mostly depends on the tape type. There is a good article about tape media lifespan which can give you some information.

How to estimate the lifespan of LTO tapes
http://searchdatabackup.techtarget.com/tip/How-to-estimate-the-lifespan-of-LTO-tapes