This isn't "a service" though, it's a different company (which LinkedIn owns). That's a third party with regards to GDPR, because, as it now happens, you can se

This isn't "a service" though, it's a different company (which LinkedIn owns). That's a third party with regards to GDPR, because, as it now happens, you can sell that company. If it was a LinkedIn-asset, that could look different (e.g. you can access YouTube with your Google Account created for GMail). But that would create another problem: if it was an asset (and not a company), you'd need opt-in from every user to transfer their user data over to the buyer, because the buyer would be a third party. It's either a company or an asset, it can't be both at the same time.