You can check out your debt collection Statute of Limitations for your state or just learn more about checking when the SOL applies to a particular debt.

When creditors push for debt payoff and its been quite some time since you've made a payment, or charged something to the credit card, then it is worth taking the time to see if the SOL has expired on the debt.
It happens so often, it is hard to believe, but too many people are paying debts they "legally" no longer owe. Don't be one of them!
Sometimes it is because you might not know how to read your credit report, you forgot or didn't keep records of the debt, payments, etc.
If you know the debt collection Statute of Limitations for your state, then you can start to research the SOL on any debt you may have.
Start with the last time you charged something to a credit card, or took out a personal loan (or had the loan refinanced).
Then look up the last payment you made on the account. Having the canceled check as proof is a good idea but not required.
Next, go to the chart below for the SOL by state, and see how much time has to pass from either the last charge you made on the account or when the last payment on the debt was (whichever is last).
For instance, if you live in Alaska, oral and written contract SOL is 3 years on each. So if you last made a payment more than 3 years ago on a debt and didn't do anything else for charges or payments on the debt since then, your debt collection Statute of Limitations has expired! You no longer owe the debt ... HOWEVER ...
That doesn't mean the debt collector can't try to collect or the creditor can't sue you and try to get a judgment. You need to do your due diligence if they try to collect.
If they try to collect and push collection actions against you, then you need to formally assert the debt collection Statute of Limitations to them. You can do this by either formal letter (if they send a letter or called you) or by legal document such as a debt collection Answer with Affirmative Claims (this document is something you should ask an attorney to help you with). It goes without saying, but I'll say it anyway ... always keep a copy of any letter or document you get or send until the debt is resolved (notice I didn't say "paid" - resolving a debt just means coming to agreement or conclusion on whether the debt is payable or not; and if payable, you have paid it.)
You will need to include the facts which will be documentation showing
the debt, the SOL, etc. in support of your claim.
If you don't assert your SOL claim, then you will lose the suit and
have to pay the claim to the creditor/debt collection agency.
It is not uncommon that a collector could say your debt is current
and valid because you made a prior agreement with the debt collection company.
You have to use caution for anything a debt collector tells you, so don't
be afraid to ask an attorney in your area if it is true or not.