Default restore, will I lose my VPP purchases?

I have 30 ipads, prepared through Apple Configurator. They have nearly 100 educational apps (some free, some purchased through the VPP program). If I restore them to factory settings, am I still able to reinstall the VPP apps? 'I'm assuming I won't have to repurchase but am a little nervous to start the process in the event I later hit a message that that licence code has already been redeemed.

Any advice would be very helpful.

Mandy