Certificate packs are digital quotas that you purchase and consume in a similar way to phone minutes.  To generate a certificate you need a certificate pack and each pack can generate a set number of certificates.

There are a number of certificate plans from 10 to 1000 certificates and with our flex plan as standard you will always have an amount of certificates available even when you exceed your quota.  See the certificate pricing page for details

How many times can i generate a certificate?  

Generating a certificate only uses 1 certificate from your quota no matter how many times it is printed etc.  You only pay for it when it is produced and this gives you total flexibility to manage costs as you go.