To sync your iPhone with the web (Pro feature), just sign up for an Hours account from either your iPhone or the web, then go to the other one and log in using the same account information.
The iPhone…
To sign up for an Hours account from your iPhone, install the Hours iOS app and go through the on-boarding screens. Choose the account type that best meets your needs and then choose "Try a taste..." to create your free account.
If you signed up for a professional account you will have web access and can go to www.hourstimetracking.com and click on "Sign in" at the top of the screen to sign in to your account on the web. The data on your iPhone and on the web will then be in sync.
The web…
To sign up for an Hours account on the web, first go to hourstimetracking.com and click the "Sign up" button at the top of the screen. You can then complete the simple form to register your Hours account.
Once you are signed up, go to Hours on your iPhone, tap gear > Get a free hours account or sign in > Already have an account? > enter account information > Sign in.
As long as you stay signed in on your iPhone and you have a data connection, your data will be synced between your iPhone and the web. If you sign out or lose your data connection, your data will get back in sync when you reconnect.