Thank you for contacting our Support Team.
First of all I would like to explain what is Memcached and how it works. Memcached is memory caching system which is used to speed up dynamic database websites by caching data and objects in RAM memory. This way you can reduce the speed your website is loading. However Memcached exist mostly within trusted networks where clients may freely connect to any server.
As you know your account is hosted on shared server and there is a firewall on the server which allows only certain connections. Memcached lacks authentication and security features, meaning it should only be
used on servers with a firewall set up to allow all connections. By default, memcached uses the port 11211 which is not opened on our shared servers. We cannot open the port for the service because all users connected to the Memcached service are able to view the information which is stored. This means that if two accounts on the same server are using the Memcached service they can review their separate information. We cannot allow this because this way the separate accounts can be hacked via the Memcached system.
Also if your application utilize memcache, that would probably means that your website is large and create many dynamic pages on the fly, so websites like this usually will not host on shared hosting. And secondly, memcached lacks of authentication which mean other user on the shared hosting is able to retrieve information from memcached if keys is correct.
You should look for Dedicated Server if you want to utilize memcache. You can review our offers here:
https://www.siteground.com/dedicated_solutions.htm
If you have further questions, you are more than welcome to contact us by opening a ticket.
Best Regards,
Daniel K.
Technical Support Team