Each Covve account is linked to a single address book (gMail, iPhone or Exchange). Covve and the chosen address book will remain in sync going forwards.
What is synced
Covve will sync all basic data for your contacts such as name, company, job title, phones and emails.
Some data which is Covve-specific such as Industry is not synced back to your address book.
Similarly, data that is not used by Covve (e.g. nicknames or birthdays) is not synchronized from your address book into Covve.
Location and address data is a special case. Covve will import address data from your contacts, process it and store the contact's country in Covve. Further changes from Covve will not be reflected in your address book.
In general, Covve will synchronize with your address book every few minutes when you're online and every few hours when you are offline.