Membership plugin – dates only in English


I’m almost done with translating Membership plugin to other language, but I can’t find where I can change this text:

Your subscription expires on: [date]

I’m referring to the ‘date’ element which is English only I can’t find a place to change that. There are few .js files related to dates (/js/datepicker/js) but changes made there are not working.

Could you help me with this?