This extension is under GPL liscense. You can view it here

By purchasing Expense Manager or J!Invoices for Joomla, you agree to be legally bound by the following terms.

1. The liscense that comes along with the purchase of any of our products is GPL.
2. The liscense that comes along with the purchase of any of our products allows you to install in multiple domains. However, technical support will be offered for one (1) live domain only. For multiple domain support, please contact us.
3. Read the GPL liscense to be aware of your rights and terms of use.
4. An infringement of any of the points above will imply the cancellation of your Joomla Finances account, and therefore, your access to the forum, future component updates and support.
5. Forum use must be polite. We don't allow bad behaviors, insults or SPAM. An infringement of this clause on the Forum will imply the cancellation of your Joomla Finances account, and therefore, your access to the forum, future component updates and support.