The 23-year-old, who shot to fame in 2011, admits he drank on a aily basis when he was trying to establish himself as a music artist, but stopped as soon as he got a job, reports femalefirst.co.uk.
"I used to drink. Heavily. I came up in pubs and clubs, so you get paid in alcohol, and, as soon as I signed a record deal, I thought, 'I just need to focus on this year. I can't have anything f*** it up'," The Sun newspaper's Fabulous magazine quoted him as saying.
However, the "Lego House" hitmaker struck up his bad drinking habits again when his album "+" sold a million copies in 2011.
"The day I started drinking again was the day the album sold a million copies and I was like, 'Right, done. Back to normality'," he said.
He might enjoy drinking, but says he won't do drugs.
He said: "I only see cocaine from time to time. If you want to find it, you can, but it's not in my circle."