The star five-eighth entered a treatment facility after he was photographed partying in a hotel room with a white substance on a table after the NRL grand final.

Copping a $30,000 fine from the league and a $100,000 suspended fine from the Storm as well as a one-game ban, Munster voluntarily checked himself into the centre last month to help him manage his "difficult relationship with alcohol".

Storm boss Justin Rodski said the 27-year-old exited on the weekend and returned to Melbourne with his pregnant partner.

Despite not being due back at the club for pre-season training until December 7, Munster was in the gym on Monday.

"He's finished his stint in his rehab clinic and he's come back in really good shape," Rodski said.

"He returned to training on Monday with some of the new guys who arrived back early and his mindset is really positive.

"We're really looking forward to him having a big pre-season and focusing on making sure he puts all the necessary steps in place to make sure he improves himself as a person and as a player.

"I know speaking to him yesterday he's really committed to that."

Munster had been linked to the NRL's latest expansion side the Dolphins, with his Storm contract expiring at the end of 2023 but reportedly sees his long-term future in Melbourne.

"He's contracted with Melbourne for 2022 and 2023 and who knows what happens after that - there's every chance if he continues the way he is he will be a one-club player with the Storm," Rodski said.

Munster's fellow Storm party boy Brandon Smith is also hot property in the recruitment market but Rodski said they are working to secure the New Zealand Test hooker.

"No doubt there will be a lot of interest in Brandon, who is out of contract at the end of 2022, so there's some discussions happening between the club and his management at the moment," Rodski said.

"We'd love to see him continue on at the Storm and we're really confident that he will.

"Over the next few weeks we will ramp up those discussions."

Australian Associated Press