Below is my nintex version and license information

Nintex Workflow 2013

2016 Nintex Global Ltd. All rights reserved.

this action is included with standard I believe.

please ask your farm admins to check the action is permissioned to you.

Hi,

For sure, "Create Item in another site" is a available in standard version of Nintex workflows.

Just make sure this actions is selected in allowed workflow actions.

Go to SP Central Admin --> Nintex Workflow Management --> Manage allowed actions --> check if "Create item in another site" actions is selected as shown below.

Thanks,

Krishna.