ExQuilla, beginning with version 24 in September 2013, requires an annual license for use. New users, by default, are automatically granted a free 60 day trial license, or a license valid until November 1, 2013, whichever is later. After that trial license expires, ExQuilla will enter a read-only mode until a valid license is entered.
One license is required for each user, using the user's individual email address on a Microsoft Exchange Server as the license key. Multiple email addresses are allowed per installation, as long as the licensed individual email address is also in use on that installation. Domain licenses are also available, which has the advantage that you only have to manage a single license instead of individual licenses.
All licenses are stored on a license server. Normally after you purchase a license, on the next restart ExQuilla will query the license server and find your license. You can also add the license (which is just some text) manually, or manually query the license server, using (within Thunderbird with ExQuilla) Tools/ExQuilla for Microsoft Exchange/Open ExQuilla license options.
Why are you transitioning to a pay model?
Simply put, because ExQuilla has from the start intended to be a business and not a hobby. ExQuilla represents years of effort, and to justify that effort and the continuing effort in support, maintenance, and improvements, it needs to generate income.
Others seems to generate their income from donations and advertising, why not ExQuilla?
Other extensions earn some income from donations and advertising, but for the vast majority of extensions the amount is typically a couple of orders of magnitude below the amount required to pay the developers at prevailing wages. I am not willing to work for the income that donations and advertising would generate (which would typically be much less than $1 per hour), nor do I think it is reasonable to expect that of others.
What are my choices if I do not want to get a license?
Earlier versions of ExQuilla will continue to work with Thunderbird 17, so you are free to continue to use versions of ExQuilla prior to version 24 with Thunderbird 17. However, if you update to the newer version Thunderbird 24 when it releases in September 2013, you will not be able to continue to use ExQuilla, as only ExQuilla 24 and later will be compatible with Thunderbird 24.
How can you expect people to pay for ExQuilla without fixing [insert your bug or feature of choice here]?
As much as I would like to have ExQuilla match all Outlook AND Thunderbird features, the current market for this extension does not seem to justify the team of 10 developers that would be required to do that. Same issue with bugs. Also, the payments for the extension contribute to the effort to improve the product by adding features and fixing bugs.
How can I see if I have a license, and when it expires?
You may view information about your license, from Thunderbird, by entering Tools/ExQuilla for Microsoft Exchange/Open ExQuilla license options. This will show your license, licensed email and expiration date, as well as allow licensing-related operations.
The email address will be used within subsequent versions of the ExQuilla addon to verify license validity. We will not send emails to the addresses from the licenses, nor will we give or sell those email addresses to others.