Where is the best place to place a base? On what service?

Question

Database

At the same time, access to the database must be through a local desktop application.

Answer 1

And you do not want to specify what database it is? And why exactly the database, and not the normal api to the database? opening a database on the Internet is generally a bad idea

Answer 2

Hire a programmer/integrator. The second is better in your case