Note that I am not licensed to practice in your state.
Federal tax liens are secured by the property itself. The governement has the right to foreclose on the house if the lien does not get paid, even if it has a new owner. Depending on how much the tax lien is, it might have been a bad investment or a good investment either way.
First, federal tax liens stay on the property when it is transferred unless they are released at the time of sale. That is why we do title searches and title insurance is issued to insure against these liens. That being said, the "last date to refile" is usually the end of the lien. That is its statute of limitations. If the IRS has not refiled the lien by that date the lien has expired.
I suggest you consult with an attorney or accountant in your area. YOu may have a valuable property there with no lien on it.