What Do I Get With Premium?
The 500-photo limit is removed. Everything else is in the free version already.
Premium removes the 500-photo limit. That is the main thing. Every feature is available in the free version, so you can see exactly what it does to your own photos before paying anything.
Exporting directly to a connected phone is the one extra that comes with it.
The free 500 is a real allowance, not a trial that expires. Unlimited is $9.99 once.