how long do joints / blunts last in a properly controlled humidor?

I would like to save 5 or so joints from each grow. I have a cigar collection and under proper storage they last a very long time. I have a nice humidor that works well, I would like to start a grow collection and possibly have a vintage selection several years down the road. Is this possible to do with cannabis with out losing potency?

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Thank you. Has anyone experimented w/ nitrogen?