no need for all the diff events. Just use the on rawmode also it's better to use groups instead of a global var for the on an off.

#thank off
On !*:rawmode:#: { 
  if ($regex($1,/\+[voh]/) && $2 = $me) {
    inc $+(%,$1) 1
    msg # 7Thanks for your [11 $1 7] [11 $nick 7] $replace($1,+o,OP,+h,Hop,+v,Voice) number:4 $($+(%,$1),2)  
  }
}
#thank end
menu status,channel,menubar {
  .Turn Snip3 Thanker $iif($group(#thank) = on,Off,On):{
    $+(.,$iif($group(#thank) = on,dis,en),able) #thank
    echo -a Snip3 thanker is now $group(#thank)
  }
}