Users will have to create a login, with all the normal information (first, last, address, city, email..etc..)

Next they will have to upload a file that contains data to be parsed out (kind of like a phonebook, company name, address, city, state zip)

That phonebook data will be compared to a 3rd party provider, and if an address matches, the address will be added to my database with a flag indicating that it has been verified so that ultimately lookups to the 3rd party will become minimized after my database grows...

I'm thinking of making the autoincrement in the user creation the primary key as a reference to what addresses they have uploaded, but not on the master database.

So would it be easier to have 3 databases?
users
phonebook upload
phonebook masterlist

or
should I just dump it all into one database with multiple tables?