After a matter of months in the St Pat's youth setup, Melia was promoted into first-team action well before his 16th birthday. In fact, he became the club's youngest player and goal-scorer aged 15 years and 132 days old when he came off the bench to find the net in a 3-1 Leinster Senior Cup loss to Wexford in February 2023. Picking the ball up on the edge of the opposition penalty area, he took a couple of delicate touches before rifling into the top corner.
Melia was then sent back to the youth ranks for a few months before returning to the senior fold in May of that year, becoming the youngest league debutant in the history of St Pat's. Even though this occasion wasn't marked with a goal, interim manager Jon Daly was full of praise: "He's been exceptional at U19s. When you are thinking 'I need a goal', I saw him score numerous goals for the U19s, I saw him score against Wexford in the Leinster Senior Cup, so I know he can finish and I know his movement is good."
That first league goal eventually arrived the following month during a 7-0 drubbing of UCD, with the national press crowning Melia as 'magic'. Within weeks, he was on trial at Manchester City and was tipped to join Liverpool, becoming more of a known quantity to teams on the other side of the Irish Sea.
The milestones kept on tumbling for Melia, who signed his first pro contract in November 2023, three days before his ascension took its sharpest climb yet. St Pat's had reached the 2023 FAI Cup final, setting up a clash with Dublin rivals Bohemians. There was international interest in the fixture, and it broke the attendance record for an Irish cup game which had stood since 1945, with 43,881 packing out the Aviva Stadium. With his side leading 2-1, Daly threw Melia on as a 57th-minute substitute to become the youngest player in FAI Cup final history. St Pat's would go on to win 3-1 and Melia had his first taste of silverware at a time where domestic football in Ireland was turning into a hot-topic again.
The 2024 season was Melia's first as an established member of the St Pat's squad from start to finish. Where he made 13 appearances and scored three goals in 2023, the striker featured in a whopping 41 games across all competitions the following year, this time netting on seven occasions. Along the way, Melia made his European debut as St Patrick's reached the league phase of the Conference League, which was eventually won by Chelsea. To cap off a memorable campaign, Melia was voted by his peers as the PFAI Young Player of the Year, becoming - you guessed it - the youngest-ever recipient of the award.
All the while, Melia was enjoying almost unprecedented success with the Ireland U17s, scoring 10 goals in 22 games at that age group either side of the 2023 Euros. He has since made his mark at U21 level, becoming Ireland's youngest scorer in that age category, obviously.