First Step:
Go to your php.ini file mostly located in C:/xampp/php/php.ini .
Then search for
;extension=php_memcache.dll
and replace it by
extension=php_memcache.dll
extension=php_memcache.dll
Note: Removed semicolumn (;)
If you do not find it then add it.
I am using xampp-win32-5.6.15-1-VC11-installer.exe with windows7 (64 bit).
(Available at https://www.apachefriends.org/download.html)
Second Step:
Now go to http://windows.php.net/downloads/pecl/releases/memcache/3.0.8/ and download latest version of php_memcache by its date unzip it and copy memcache.dll file and paste it into C:\xampp\php\ext
Third Step:
Now restart XAMPP.
Fourth Step:
Now to check whether it is installed or not create a file phpinfo.php and paste below code in it and Run it in your favorite browser.
<?php
phpinfo()
?>
Fifth Step:
Search for keyword Memcache.