Local database choice (Windows Phone 8.1 application)

I am in the process of making a relatively complex Windows Phone 8.1 application and I need a way to store data from server's database into a local database. Data from server is retrieved in JSON format via API. What are my options here? I've tried SQLite database controlled by sqlite-net but it lacks key features such as foreign keys support and 64bit support (?). What other choices do I have? Local database is used in order to give the user ability to work offline and later sync the data from local database with server's database.