By the grace of God, He has given man a means to shorten punishment owed Him, since God is the offended Party by man's sin. Thus, punishment due a man that was not satisfied on earth can be satisfied in purgatory. Indulgences, whether they be alms, fasting, or prayer, are all considered worthy of pious praise and move us closer to God. Our Lord never did away with any of these pillars of Judaism.
Regards
Yes, by His death and resurrection the price has been paid. All those whom Christ came to redeem stand blameless before God because He took upon Himself to pay for their sins, as ordained by our merciful God from before the foundation of the world.
To add further requirements to Christ's perfect atonement is to belittle the gift itself.
Did Christ pay for your sins, or not?