Which CardExchange Gateway edition do I need?

There is a lot of functionality to consider when choosing the correct edition.
Here are some of the key features:

Go edition

Internal database limited to 200 records
Limited to 5 card templates

Premium edition

Can connect to csv, Excel, Access and SQLite databases
No limit on the number of records
No limit on card templates
User based logins

Professional edition

Can connect to MySQL, SQL Server and Oracle databases
Automated face-Cropping built in
Group based logins
Conditional layout support

Business edition

Support for Mifare Classic encoding
Support for reading HID Prox cards and iClass UID numbers

Enterprise edition

Support for Mifare Desfire encoding
Connect to LDAP to read/update records

A full list of features for each edition can be found here.