Why upgrade? Unlimited Contacts and Companies
Premium users can have an unlimited number of Contacts and Companies.
Contrast that with up to 25 Contacts and up to 25 Companies for the Regular level (which is free). If you are only putting Contacts and Companies that you are really working with, or seriously want to work with, it might take you a while to max out the limit on the Regular level.
Note that if you import more than 25 Contacts or 25 Companies during any Premium trial or upgrade that you have, when you go down to the free level you will not lose any of your Contacts or Companies. You won't be able to add more, if you are over the limit, but any Contact or Company you put into the system will always be fully available to you, even if you go to the free level.
Everything is in the free version, except these features: