WordPress multisite for multilanguage domain

[Fuad]

I added a subdomain in wordpress multisite because I want to add other languages to my website. I created es.mysite.com to make my site in spanish. I activated UserPro plugin in my subdomain and there is a message saying I am using a trial version of UserPro plugin, and invite me to enter purchase code to enable full version.

Is it safe to enter purchase code in my subdomain. I need to have full version to work in my subdomains for different languages.

Hope to hear from you soon.
Thanks in advance.