I will upgrade your Prestashop store (from 1.4) to the last version without any loss of data, so you will keep all of these informations: . Products I will do a full backup of your website that I will copy on a temporary URL, so you can validate the new version without turning off your old one. Once you validate the new version, your old website will be turned off during 1-2 hours. Important note: if your theme or modules need paying upgrades, you will have to buy a new licence for each one.