No, no subscription will be made when purchasing TAPICall.
TAPICall is always prepaid for 2 years.

No, TAPICall is not a TAPI driver.
TAPICall is a CTI software that requires a TAPI driver to work. Alternatively, TAPICall can be connected directly to a FRITZ! Box, but you will NOT receive a driver, but the ability to use TAPICall to make and receive calls.

This behavior is often the case. After a Windows update, Microsoft restores many services to a default value. This also applies to the service "telephony" which is essential for all TAPI drivers. Open the services in Windows, there select the service "Telephony". After a right-click, select the item "Properties". Now set the startup type to automatic, then confirm this entry with "Apply". Restart the computer now.

An Exchange server is suitable for this purpose.
There, you create a public contacts folder and grant access to all employees. If you do not want to run a local Exchange server, you can alternatively use the Online Exchange from Microsoft.

Yes, TAPICall can also be installed on a terminal server.
For each session to get a valid license, a few adjustments are necessary. These are in our Terminal Server Guidelines described.