how long does each plug last?

I've been using these for about 5 or 6 years as I write this in 2018, and with daily use, I get about 2 months from each plug. For anyone who doesn't use them daily, my travel pair only gets used once or twice per month, on average, and they've lasted much longer. I'd estimate I've had the same travel pair for about 2 years. If they get a bit stiff, I work them until they are pliable again, and they work great.

What is noise reduction rating (nrr) of the product?

I don't know, but I can only offer my personal experience with this product. I have tried MANY earplugs available at pharmacies and after doing some online research found these. They are the best I've ever tried and I always reorder. I used to live in a small, 2 bedroom apartment with a 12 year old boy who had friends over. They would do what boys do at that age and I need to get to sleep by 10PM the latest. Despite all the noise they would make (and my son's room is next to ours) I slept very soundly, I wouldn't hear a peep.

What ingredient makes them blue? Seems unnatural

The blue is food coloring. The product is 100% natural. Made of cotton, bee's wax and lanolin. I swear by these plugs. I use them for shooting at indoor and out door ranges around high caliber rounds. I am not affected. I chose these over bulky cans/headsets. The key is making sure you fit the plugs in to leave as little air space between your eardrum and the plug. Be sure it is well sealed with no contact with outside air. Hope this helped. http://earplugsonline.com/

what is the best ear lug to prevent hearing snoring

I have tried foam plugs, silicone plugs, noise canceling earphones 250.00. , ring plugs...by far , these cancel snoring, large mowers outside, 500 elementary school kids 30 ft. away screaming, ....neighbors having parties, kids yelling a nearby pool.....air conditioners, road work, etc .....these are the real deal...using them for 9 years....they have saved me.