51Degrees Version 3 API is available on Kentico 8.1 and higher. Please see release note
Release notes - Kentico 8.1
Regarding the renaming of the data file, the API will use embedded Lite data if it can't find the file. The API will work but you won't get any premium properties.
I feel your options are;
[list=1]Upgrade to Kentico 8.1 or higher
Remain on Kentico 7.0 and switch off ShareUsage
Manually update the 51Degrees DLL to version 3 and update all the configuration
For the last point, I don't know how Kentico will handle this change and where it will break.
Hope this helps.