When it comes to shelf life, you should know that prepared horseradish has some preservatives, so its shelf life is pretty long. As long as the bottle is unopened, its suggested shelf life is about a year. Of course this is only a rough estimate and it probably will be safe to eat for a lot longer.
http://www.doesitgobad.com/does-horseradish-go-bad/
Here's how long the Food Safety and Inspection Service says you can safely refrigerate certain things after they've been opened. (You can check other foods by using the Food Keeper feature on the Food Marketing Institute website.) Ketchup, cocktail or chili sauce: 6 months; Chutney: 1 to 2 months;
http://www.consumerreports.org/cro/news/2012/04/how-long-to-keep-ketchup-and-other-common-condiments/index.htm
I always keep a jar of store-bought preserved horseradish in my fridge. In a pinch, it's a perfectly good product, whether I'm whipping up cocktail sauce for poached shrimp or sitting down to a jar of gefilte fish for a light and lovely afternoon snack—and, as lovers of gefilte fish, we all know it's fantastic with horseradish.
http://www.seriouseats.com/2015/07/how-to-prepare-fresh-horseradish.html
(You can check other foods by using the Food Keeper feature on the Food Marketing Institute website.) 1  Ketchup, cocktail or chili sauce: 6 months; 2  Chutney: 1 to 2 months; 3  Horseradish: 3 to 4 months;  Mustard: 12 1  months; Pickles and olives: 2 weeks;  Mayonnaise and salad dressing: Up to 2 1  months; Barbecue sauce: 4 months;
http://www.consumerreports.org/cro/news/2012/04/how-long-to-keep-ketchup-and-other-common-condiments/index.htm
How to tell if prepared horseradish is bad? If it’s bad, it will be pretty obvious to you. Just check its appearance (look for mold), its smell (if it developed an off odor) or taste. If any of those things are as they are supposed to be (off odor, sings of mold or it tastes bad), just discard it.
http://www.doesitgobad.com/does-horseradish-go-bad/
Horseradish products are best when fresh since they will lose a little “heat” every day after we grind it. Kelchner’s Horseradish Products will stay fresh for roughly 5 to 8 months from the time of production (assuming the product has been properly stored in refrigeration). Opened jars will lose their heat and flavor faster and may only keep for 1-2 months in the refrigerator. Kelchner’s Hot Mustard and Tartar Sauce have a one year shelf life from the time of production and don’t require refrigeration. All Kelchner Products should be refrigerated after opening.
https://kelchnershorseradish.com/contact-us/faqs.html
Once they're open, the more time the enzymes have to work their way through the prison and free those prisoners, the more prisoners will escape, making the air and flavor even more pungent. So, the longer you wait to add the vinegar, the stronger the horseradish will get.
http://www.seriouseats.com/2015/07/how-to-prepare-fresh-horseradish.html
Refrigerate after opening. Storage time shown is for best quality only — after that, the horseradish's texture, color or flavor may change, but in most cases, it will still be safe to consume if it has been kept continuously refrigerated.
http://www.stilltasty.com/fooditems/index/17417
Tips. 1  Refrigerate after opening. 2  Storage time shown is for best quality only — after that, the horseradish's texture, color or flavor may change, but in most cases, it will still be safe to consume if it has been kept continuously refrigerated.
http://www.stilltasty.com/fooditems/index/17417
Then just seal it up in an airtight container and keep it chilled. It'll keep at least a few weeks, if not longer, in the refrigerator. Try this stuff in your cocktail sauce or horseradish cream, or (most likely) on your gefilte fish, and that jar from the supermarket may end up forgotten at the back of the fridge.
http://www.seriouseats.com/2015/07/how-to-prepare-fresh-horseradish.html
how long does horseradish sauce keep after opened
Horseradish sauce keeps 1 to 2 months in the refrigerator after opened. Keep a horseradish sauce for 1 to 2 months in the refrigerator after opening.