you will know when you can longer pass the tape. The "coating" (oxide) will start peeling off. It is good for practically limitless amounts of passes. Tape will be there tomorrow unless you get it to close to a speaker, amp, etc. motors are bad also. Keep you tape off the top of the 'fridge, there is a magnet in that there thang. Also store in tails out, or you will get "undesirable" print through.