Memory usage increasing over time.

When I start my server and it's been running for an hour or so it's using;

Memory RAM (with Cache): 2.58GB / 32GB
Memory RAM (NO Cache): 1.49GB / 32GB
Number of processes: 234

After 20 days it's using 27gbs of ram and over 350 processes are using. This seems a gradual increase as I've watch it creep up day by day. Question is;

Should I be concerned and if so how can I find the problem and solve it.

CentOS release 6.8 (Final)
Apache version: Apache/2.2.27
PHP version: 7.1.0-dev
MySQL version: M
FTP version: 1.0.36
CWP version: 0.9.8.36
I don't run av or spamass because I don't use the email server. I also shutdown ftp when not in use.

simply drop the cache (openvz will not applicable here)

if this memory is in the cache then you can ignore it as cache speed ups you server, if its something else they you would need to check it.