Provided always, That no person or persons shall be sued, impleaded, molested or troubled for any offence against this act, unless the party offending be sued or impleaded for the same within two years at the most after such time wherein the offence shall be committed, in case the party grieved shall not be then in prison, and if he shall be in prison, then within the space of two years after the decease of the person imprisoned, or his or her delivery out of prison, which shall first happen.