The 4.5 partner licence keys can be used in SD5 but you need to modify the dat file. You install them using HP OpenView Service Desk Licensing
Start Autopass, then use 'import file' - select your DAT file, then after opening it, you should see a list of licenses. You then must select the specific features (there are 5) and after validating them they should show up as green, indicating they are valid at the moment of importation.
You need to edit the dat file so that the licences show in the following way;
XXXX XXXX XXXX XXXX XXXX SSSS XXXX XXXX "Partner Key 15 named users Service Desk 4.x"
Note the quotes and that the key an anotation are on a single line.