[dannyr]

I didn't dive deep into the source code.

Does it invalidate a coupon after it's used?

What would happen if I get a new phone? Would I need to get a new coupon?

[zemariamm]

Currently you can't control the number of times a coupon has been used, but you can control its lifetime. If you get a new phone (and the coupon it's still valid) it will work, otherwise it won't.