Assalamu Alaykum. We humans are bound to sin, but when a muslim(say xyz) will be thrown in the hellfire and after his(xyz) punishment is over, will the residents of Jannah still remember his(xyz) sins after he enters Jannah. If xyz robs something and enters Jannah after serving punishment in hell, so will the people of Jannah still remember his sins.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His Slave and Messenger.

We do not know of any evidence suggesting that the people of Paradise will remember the sinner's misdeeds after he enters Paradise. What we know is that in Paradise nothing will embitter the bliss that the dwellers of Paradise enjoy therein. As the people of Paradise enter it, they will relish its enduring blessings; there will be no trace of grief or distress therein. Allaah Almighty says (what means): {Indeed, the righteous will be in gardens and pleasure}[Quran 52:17]

In an authentic Hadeeth, Abu Sa‘eed Al-Khudri reported that the Prophet said: "There would be an announcer (in Paradise) who would make this announcement, 'Verily there is in store for you (everlasting) health so that you never fall ill, and that you live (forever) and never die, and that you remain young and never grow old, and that you relish a constant bliss and never feel miserable.'" [Muslim]

The inhabitants of Paradise may remember the fear they felt for the punishment of their Lord and they would thus realize the greatness of the blessing bestowed upon them by entering Paradise. Allaah, The Exalted, says (what means): {And they will approach one another, inquiring of each other.* They will say, "Indeed, we were previously among our people fearful [of displeasing Allaah].* So Allaah conferred favor upon us and protected us from the punishment of the Scorching Fire.}[Quran 52:25-27]

Allaah Knows best.