Your bait is probably still good, especially if it has been in a sealed container.
I have used ancient bait with the same results as fresh bait.
The ban on anticoagulant bait is based on junk science, environmental hysteria, and ignorance and has had some very disturbing unintended side effects.
Some scientists found that some wild animals had some levels of brodificoum in their system so all anticoagulants have been banned.
It's hard to get an "enviromentalist" to accept that a little bit of the same compound that is regularly used in human medicine is not harmful. It is even harder to get them to understand that the methods they used to come to their conclusions may be flawed.
Rodent baits have bitrex and ipecac added to make the bait less palatable to non targets and to induce vomiting, which rats cannot do, in the case of accidental ingestion. A predator would have to consume gluttonous amounts of poisoned rats to get any significant exposure to the active ingredient.
Here's the kicker
With those anticoagulants that have been around for decades there is a known, commonly available and easy to administer antidote, that is also commonly found in pet food.
There is no known antidote for the bromethalin and the life saving treatment window is a few hours instead of several days
It also seems to have a lower LD50 than the old baits
