Non-Capturing Group(?:^mem:|\G(?!^)) ^start of line
mem:the literal text mem: (case sensitive) \Gstart of current search
\s+any whitespace character, repeated at least once
\Kresets the starting point of the reported match. Any previously consumed characters are no longer included in the final match
\d+a digit, repeated at least once
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string