64 Pa. Stat. § 415
The secretary of the land office of this commonwealth be and he is hereby authorized to settle the accounts of all persons who may apply for patents, either by themselves, their agents or attorneys, and be entitled to the same, on or before the first day of May, 1817, and who are indebted to the commonwealth for the purchase money of lands and interest due thereon, and on the payment of the usual fees of office the said secretary of the land office shall issue patent or patents to such persons for his, her or their respective lands, and on the same patent or patents certify the amount of the purchase money and interest due for the land therein described, which aggregate sum shall bear interest from the date of the certificate, and shall be and remain a lien on the said land until the money shall have been paid; and such persons receiving patents as aforesaid, their heirs and assigns, shall be permitted either at the time of issuing the patents or at any time thereafter, to pay the whole or any part of the interest and of the aggregate sum aforesaid, and receive a credit upon the patent for the same.
64 P.S. § 415