Can I rejoin after cancelling my membership?

How can I check my Joycity membership number?

I’ve lost my registered Facebook or Google Plus ID.

I’ve lost the password of my registered email ID.

I lost the email account that I’ve linked.

How can I check if I have properly linked my account?

Is it okay to just link to Google Plus? (For Android only)

How do I link my account?

If I change my device or reinstall, can I still find my old data?