Speaking to the Star, Robbo explained: "He has done well and earned the chance of a contract through his performances.
"He's been professional all the time he's been here, even when he was here pre-season and we didn't take him on then, and now he's getting a chance."
Drewe will look to continue his good form with a goal as the side travel to Brentford tomorrow in that start of a tough month which also sees games against Chesterfield at Saltergate and last year's play off losers Rochdale.