ADINA version 9.9 and later uses Subscription Entitlement Service (SES) for licensing. With SES there is generally no need to check out a license. So long as there is a periodic internet connection the software will verify entitlements and function for up to 7 days offline. There are some cases where a machine may be offline, and this requires a license to be checked out. The procedure to check out a license to such an offline machine is detailed here: How to check out licenses for offline machines.
With ADINA, it is important to check out the correct tier; ADINA, ADINA Advacned or ADINA Ultimate and select that same tier when opening the application. If the ADINA Parasolid Modeler is to be used, then it should also be checked out. This can be done with a single checkout by Adding ADINA Parasolid Modeler before clicking [License Checkout].
Once you get to the License Checkout screen https://connect-entitlementmanagement.bentley.com/entitlement/license_checkout follow these steps:
For guidance on using a checked out license on Linux, see: ADINA Installation & Licensing for Linux