I am a freelance designer/developer and i'm currently working on an ecommerce software which i plan to license to my clients (monthly). We're almost ready to roll out the software, but I thought I should check if any contracts or agreements are required.

Do most ecommerce software companies require you to sign a contract/agreement before you chose to use their software? Maybe one that does not leave them responsible if something happens to your site (eg. hacked).

If anyone has any useful knowledge about this area, please let me know.

Your help is greatly appreciated.