I often hear that advertisers refuse to let clients behind the curtain. They won’t use the client’s ad account because it would give them access to everything: How they set up each campaign and “the secret sauce.”
They’re afraid that the client could see how those The campaign is the foundation of your Facebook ad. This is where you'll set an advertising objective, which defines what you want your ad to achieve. More were set up and do it themselves. They’d cut out the advertiser.
If what you provide is so basic that it can simply be copied forever, you are replaceable.
Be okay with the client continuing your campaigns when you’re gone. Nothing lasts forever. Those campaigns will stop working. Meta will change their rules. New features emerge.
Expertise will be needed. Then what?
How you set up a campaign isn’t your secret sauce. A good client knows that, too.
What makes you special is your knowledge, expertise, and ability to react. Your value is that you solve problems. You are constantly evolving. And you know what to monitor and tweak to get your client optimal results.