If your advertising runs through an external agency, there is a fair chance that the accounts, the pixels and the accumulated data are registered in that agency's name, not in yours. You pay for the media, but the memory (the data and the learning curve) builds up outside your company. That matters more now that marketing increasingly runs on AI: an AI layer can only make good decisions for you if it learns from your own data. If that data is not yours, you are not building a marketing brain of your own. Since the European Digital Services Act, Google, Meta, LinkedIn, TikTok and Microsoft publicly show who pays for an advertisement. In two minutes you can check the public ad library to see whether that is your own name, or your agency's.
That is how long it takes to look up who pays for your ads. Go to the platform’s ad library, type in your company name, open an ad and look at the field marked "Paid for by". No account needed, no cost.
01Why can you publicly see who pays for your ads?
The European Digital Services Act requires large platforms to maintain a public ad repository. For every advertisement it shows who advertises, who pays, in which period the ad ran and in which countries. The obligation applies to ads shown to users in the European Union. A campaign that only runs outside the EU will not appear.
The field that matters is usually called "Paid for by". The platform fills it with the verified payer behind the advertisement. For a company that advertises itself, it shows the company's own name. For a company that advertises through an agency, it sometimes shows the name of that agency.
02Where can you look it up?
The platforms where most companies advertise have a public library you can search without logging in. Click one of the four below, type in your company name and set the country to Belgium, the Netherlands, or wherever your ads run. Then check the payer field. The full list of libraries follows below.
The Digital Services Act requires every designated very large platform and search engine to keep such a public ad repository. The European Commission maintains the current list. Beyond the four above, these are the other places you can search. Quality varies: some only work through an API, only show EU ads, or load slowly.
Ad platforms
- X Ads Repository EU ads with advertiser, funding party, targeting, impressions and reach.
- Microsoft Ad Library Search ads on Bing in the EU and EEA.
- Pinterest Ads Repository EU ads, public but heavily dependent on JavaScript.
- Snap Ads Gallery EU ads from the last twelve months.
- Apple App Store Ad Repository Ads shown in the App Store in EU countries.
Marketplaces and retail media
- Booking.com Ad Repository Ads shown on Booking.com in Europe.
- Amazon EU Store Ad Library Ads and affiliate content from the past year. Runs through Amazon.de and can load slowly.
- AliExpress Designated as a very large platform under the DSA.
- Zalando Ads Repository Public repository, also reachable through the local stores.
03How do you look it up, step by step?
IN FOUR STEPS
Finding the payer yourself
- 01Open the platform's ad library. No login or account needed. It works in any browser, including on your phone.
- 02Type your own company name in the search bar. If several entities or locations appear, pick the right one. Set the country to where your ads run.
- 03Open one of your active ads. Click the ad, or the menu next to it, to see the details.
- 04Look at the payer field.Does it show your own company name, or someone else's?
If you first want to see what it looks like without your own numbers involved, search for a large brand you know, a national retailer for example. You will see their running ads, and the payer field shows their own name. That is how it should be: the brand that advertises is also the payer. The question is whether the same is true for you.
04What does it mean if the payer is your agency?
If the payer field shows your agency's name, your ads run in that agency's ad account, not in yours. That is not wrong by definition. Many agencies work this way, and for some clients it is perfectly fine. But it has consequences you rarely see yourself.
THE CONSEQUENCES
What it means when your agency is the payer
- DATAThe history lives in their account. The accumulated campaign data and learning curve are registered to the agency. If you switch agencies or launch a new website, you often start from scratch.
- ALGOThe algorithm learns at account level. The platforms optimise within the account where the campaigns run. That learning curve does not move with you when you leave.
- KPIWhoever manages the data decides what you measure. For reporting you depend on what the agency shares from their account. Connecting ad results to your own revenue and customer value becomes difficult.
- AIYour own AI cannot learn from it.An AI layer needs your spend, leads, margin and customer value, connected. If that data stays in your agency's account, a system that learns for you cannot reach it.
This is not proof that anything is wrong. It is the start of a conversation. The only way to know for sure how things are set up for you is to ask your agency.
05What does a healthy setup look like?
The clean route is simple: you own the accounts, the agency gets access. Not the other way around. Both Google and Meta have built this in.
At Google, an agency can manage your account through a manager account (MCC). The owner of that manager account has full access, including personal data attached to the account. The client account remains the owner of its data and can break the link at any time. Make sure your company owns the account and the agency is linked as a manager.
At Meta, it works through partner access in your own Business Portfolio. You assign the agency specific assets, such as your ad account, page and pixel, without the agency becoming their owner. According to Meta, your Business Portfolio remains the owner of the assets, even while the agency manages them.
THE RIGHT SETUP
You own it, the agency gets access
- YOURegistered to your company. Ad accounts, Meta Business Portfolio, pixel and conversions API, GA4, Tag Manager, Merchant Center and your CRM. This is your property.
- THEMThe agency gets access. Through manager access at Google or partner access at Meta. They manage, you own. If the relationship ends, you revoke the access and keep the history.
- BILLBilling on your own payment method. That way you keep sight of the real media cost, and your spend is not hidden inside an agency account.
06What does this mean for your AI position?
Marketing is shifting to AI. The ad platforms push in that direction themselves: Google and Meta optimise on the data inside the account where your campaigns run. And more and more companies build their own AI layer on top of their marketing, to steer on revenue and customer value instead of clicks.
Both depend on data. Whoever owns their own data can feed that AI and carry the advantage forward. Whoever leaves the data with the agency starts over after a switch, or stays dependent on what the agency chooses to share. The advantage is cumulative: every month of your own data makes a model better and a benchmark sharper. That time cannot be bought back later.
None of this is a reason to cancel your agency contract tomorrow. It is a reason to make sure, today, that the accounts and the data belong to you. Then the choice stays yours, not with the account your campaigns happen to run in.
07Which questions do you ask your agency?
Three questions are enough to know where you stand. They are reasonable questions, and a good agency answers them without hesitation.
THE CONVERSATION
Three questions for your agency
- 01In whose name are the accounts and the pixel? Are they registered to our company or to yours, and can we get admin access?
- 02What happens if we stop working together? Do we keep the accumulated history and the data, or does it stay with you?
- 03Where does our lead data end up? Is there a data processing agreement, and do we know which systems handle our customer data?
The point is not that agencies are untrustworthy. The point is that ownership of your own marketing data should be a choice you make deliberately, not something that happens to you because you never looked at that one field. Two minutes in the ad library, and you know where you stand.
"Wonder en is gheen wonder." · Stevin