Appearing in the Supreme Court in Launceston yesterday, Benjamin Michael Goddard pleaded guilty to one count of armed robbery, committed on March 13.

The court heard Goddard, who was staying in Canning St, Launceston, after arriving in the state just two days earlier, told the two female staff members to "open the f --- drawer or I'll f--- kill you".

They instead retreated to the back of the store, prompting him to say "fine, I'll get it my f--- self".

He then escaped with the $1048 cash register, containing $366.70 cash.

Crown prosecutor Virginia Jones said he was arrested soon after and made full admissions of the crime, saying he was drunk at the time.

His lawyer told the court his client came to Tasmania to escape his drug-addicted past.

But Goddard's NSW associates allegedly warned him to pay his outstanding drug debts or his family - still in NSW - would be targeted.

His lawyer submitted it was the threat that prompted the armed robbery.

However, in handing down his sentence, Chief Justice Ewan Crawford described Goddard's early guilty plea as the only mitigating factor.

He must pay $1414.14 compensation to Davies Grand Central and will not be eligible for parole until he has served 18 months of his sentence.