When you take over keepership you should contact Petlog, either by phone or via the web. You should have received the registration details from the breeder, which then enable you to complete the transfer of keepership.
With a Petlog online account - you can update your email address, mobile and daytime numbers free of charge. To change your address or transfer keepership at any time then you will be charged a nominal administrative fee of £10. However, we recommend upgrading to the Petlog Premium service for £17, which allows any number of updates to your details over your pets lifetime.
Once this has occurred, a registration confirmation certificate will be sent by email or post from Petlog. Please check this carefully for any errors, and keep it for your records, as it will contain the relevant information required if you need to change your details in the future. If you do not receive confirmation within 14 days, please contact Petlog on 01296 336 579.
Legally a dog isn't microchipped unless its details are recorded on a database and kept up to date.
The simplest route is to go their website:
https://www.petlog.org.uk/