Apparently there is Varnish caching HTTP reverse proxy in front of your Apache server, which is serving the cached copy of the image (because it was configured to do so).
You can observe that from HTTP response headers:
$ curl -v -s https://shop.olamsvi.com/pub/media/catalog/category/Picture1_2.png -o file.png
* Trying 52.163.125.20...
* TCP_NODELAY set
* Connected to shop.olamsvi.com (52.163.125.20) port 443 (#0)
...
> GET /pub/media/catalog/category/Picture1_2.png HTTP/1.1
> Host: shop.olamsvi.com
> User-Agent: curl/7.54.0
> Accept: */*
>
< HTTP/1.1 200 OK
< Date: Mon, 04 Jun 2018 11:52:41 GMT
< Server: Apache/2.4.6 (Red Hat Enterprise Linux) OpenSSL/1.0.1e-fips PHP/7.0.21
< Content-Length: 410771
< Accept-Ranges: bytes
< Access-Control-Allow-Origin: *
< X-Frame-Options: SAMEORIGIN
< X-Varnish: 41773
< Age: 0
< Via: 1.1 varnish (Varnish/5.2)
< X-Original-Content-Length: 561788
< Etag: W/"PSA-aj-giNrXrkKdK"
< Expires: Fri, 22 Mar 2019 05:53:09 GMT
< Cache-Control: max-age=25120827, public
< X-Content-Type-Options: nosniff
< Content-Type: image/png
<
{ [16384 bytes data]
* Connection #0 to host shop.olamsvi.com left intact
Not the Via: 1.1 varnish (Varnish/5.2)
and Expires: Fri, 22 Mar 2019 05:53:09 GMT
lines.
It is usually very beneficial to cache your static resources, but you should also think about the way how to invalidate it (and when to do it)