The 26-year-old midfielder opened the scoring after a superb give-and-go with Jordan Henderson before slotting the ball effortlessly into the far corner.
And the former Saints midfielder is delighted to have got off the mark - and even more so to have helped the Reds secure a 2-1 win against West Brom.
"A lot of my feelings were represented in my celebration," he told Liverpool's official website.
"It was a proud moment and a bit of relief, as it's always nice to get off the mark. But, more importantly, we got the three points and that is a step in the right direction."
The England man, who moved to Anfield for £25 million this summer, also set himself a personal goal target for the campaign.
At Southampton last season, Lallana scored nine times in the Premier League. He wants to go at least one better this time around.
"I got nine in the league last season so it would be nice to get double figures," he added.
The international break means Brendan Rodgers' side now have two weeks of rest, although many of the Liverpool squad will be in action for their countries.