I insert the written label inside the vial and "plant it" vertical where I sown seed for a waterproof name tag for later identification. The vials can also be written on directly and easily erased for later use! Just simple soak it in rubbing alcohol and wipe off.
Each vial is discreet, easily hidden but also readily recognized when retrieving as well.
Note the last two photos. I have used every product there is out there and mine have withstood the test of time. Unlike others, mine are still legible and intact. The last photo is from one seasons' end!
* Be sure to store seed when Completely Dried*!!! I wait at least 3 months just to be sure all moisture has gone. I also use paper products (bowls, plates, sacks, etc.) to help wick away any remaining moisture.