In most cases, updating should be fairly straightforward forward. Efforts have been taken to map the previous settings to Age Gate 3.
However, it is always advisable to update any plugins in a non-live environment first to ensure functionality is as expected.
If you have any problems, let us know via the support forums.
Updating from v2.x to v3.x
Efforts have been taken to ensure a smooth update from v2 to v3, but v3 should be considered a breaking change and it is advised to test the new version in a development environment first.
If you are really having problems, your Version 2 settings remain in the database (for now) so you can easily downgrade to a 2.x version of Age Gate. You can find previous versions of the plugin on the WordPress plugin site, which you can then upload via the admin area of your site.
Updating from v3.x-dev to v3
If you have been using a development version of Age Gate 3 in production, note that the final release will differ in functionality so again, check the latest version in a staging or local environment before updating.