пример я обновил

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http {
# allocating 10Mb for counetr with name "host_counter"
# and hashing function by $client_ip
counter_zone host_counter $client_ip 10m;

# same for "hit_counter"
counter_zone hit_counter $client_ip 10m;

...

server {

...

location ^~ /some/stats/ {
counter host_counter 1; #increase host_counter by one
}

location ^~ /some/stats/hit/ {
counter hit_counter 3; #increase hit_counter by some other value
}

location ^~ /some/other/stats/ {
counter host_counter $inc_var; #increase counter by some variable atoi
}

location ~* /stats/get_counter/(?P<id>.*)$ {
counter_get host_counter $counter $id;
return 200 $counter;
}

location ~* /stats/counter_get/(?P<id>.*)$ {
counter_get host_counter $counter $id;
return 200 $counter;
}

location ~* /stats/counter_drop/(?P<id>.*)$ {
counter_drop host_counter $id;
}