Lupco Ristevski, whose criminal record numbers more than 100 pages, was shopping inside Woolworths at Warilla Grove on the afternoon of July 21 last year when he spotted the victim in the aisles.

Documents tendered to Wollongong Local Court said Ristevski began following the 83-year-old victim, who had her Prada purse - a gift from her grandchildren - in a green recyclable shopping bag hanging from her trolley.

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He pounced when she was in the fresh produce section and had her back briefly turned, quickly reaching into the green bag and taking her purse, which he concealed under his jumper before leaving the store.

The victim only realised the theft had occurred when she approached the check-out to pay for her groceries.

The matter was reported to police, who obtained CCTV footage clearly depicting Ristevski's actions.

The victim said the purse was worth $1,000 and it contained $400 in cash when taken.

Ristevski was subsequently arrested and charged with stealing from a person.

He pleaded guilty to the charge in court on Wednesday, saying he couldn't remember the incident but regretted it.

"I took prescription medication beforehand," Ristevski told the court.

"I'm very sorry, I want to give the lady back her money."

His lawyer, Laura Fennell, said Ristevski had been sentenced earlier in the year for several similar matters but this charge had unexpectedly been prosecuted separately.

She said Ristevski, now aged 46, had abused drugs all his life and most of his crimes had been property-related.

Magistrate Claire Girotto largely overlapped Ristevski's fresh sentence with the sentence he was already serving, effectively adding only a month onto his overall non-parole period.

He will be eligible for release on parole in February 2023, at which time he must begin repaying a $1,400 compensation order.