Yes, although you don’t need to.
For starters, you should find no legal reasons that prevent you using Kee Vault - the sensitive data NEVER leaves the devices you control. It is stored remotely only in an encrypted format that can’t be decrypted, and in all likelihood even this encrypted data is stored with a degree of protection that exceeds most local protection and legal requirements.
That said, I know that some organisations have change procedures tedious enough as to make it impractical to open up a secure connection to the Kee Vault service in a reasonable time frame, regardless of the actual legalities.
Additionally, nothing will change unless you ask it to. Kee Vault is an additional password storage option rather a replacement for the existing KeePass storage option. You can’t accidentally move your existing data into Kee Vault.
Your Kee extensions can safely be upgraded to version 3 but if you want to prevent updates you can do so with the controls that your browser offers (it’s not something Kee can control).
I’d strongly recommend against that for any user, but especially so if you’re in a place where you’re concerned about the legalities of encrypted data storage locations. Disabling automatic updates to any software that may deliver security fixes in future would be against some laws and all good practice guidelines.
I’m glad you’ve found Kee useful over the years and I hope to be able keep pushing out improvements for many years to come!