Run a Software Proof of Concept Before You Buy More From Your Current Vendor

A software proof of concept is a short test of a tool on your own data, run before you sign. It matters most when you buy more from the martech vendor you already have, because those upgrades often skip both the competitive review and the test.

A mid-market B2B company was coming up on renewal for its marketing automation platform . The vendor offered a higher tier that bundled generative content tools and AI lead scoring . The marketing ops lead and the CMO signed it without a competitive review and without testing it on their own data.

After 9 months, 4 people had opened the content tools, and most of what they generated needed a heavy rewrite before anyone could use it. The predictive scores were landing in the CRM , but they weren’t changing which leads sales worked first or how many converted. The upgrade cost about $42,000 for the year.

Nobody on that team was careless. They made the same call Arthur Sadoun, chairman and CEO of Publicis Groupe, says more big advertisers are making with agencies. Instead of a months-long pitch, clients are “kicking the tires of the partner they are interested in” (1. Clarke, 2026). The team did half of that. They dropped the pitch, and they dropped the tire-kicking with it: a software proof of concept, meaning a short test of the upgrade on their own data before signing.

What did the team skip when it signed?

Their reasons for skipping a review were sound. The vendor already knew their data model and processes. The renewal window was short. The added cost looked small next to the existing contract. Running a bake-off against other platforms for an add-on would have cost more than the add-on.

The test was a different matter. They described the job as “better content and smarter scoring.” That’s a wish. Nobody wrote down which leads should score higher, what sales would do differently with the score, or how they’d know it worked. And nobody ran the scoring model against the company’s own win and loss history to see whether the data could support it.

So they bought the upgrade on the vendor’s description of it, with no evidence it would work on their own leads.

Why do upgrades from your current vendor get the least scrutiny?

Selling more to existing customers has become a large share of how software companies grow. Benchmarkit, a firm that publishes annual operating benchmarks for B2B software companies, found that 40% of new annual recurring revenue at the median company now comes from expanding existing accounts (2. Benchmarkit, 2026). A rep selling you a tier upgrade is working toward that number, and a renewal, when you’re already negotiating, is a natural moment to ask.

Renewal is also where packaging changes reach you. On September 3, 2026, Salesforce replaced its Enterprise, Unlimited, and Agentforce 1 editions with new Core, Advanced, and Max editions that bundle AI agents, Slack, and analytics into every tier. Pricing for existing customers on the old editions stays the same (3. Salesforce, 2026). That leaves the move to a new edition for a later conversation, and for most customers I’d expect that conversation to be the renewal.

Jay Friedman, co-founder of CartographAI, an advisory firm for brands, agencies, and martech vendors, describes the pattern from the buyer’s side. Each platform keeps adding features that overlap with tools you already run, until a team has 3 tools for one job. He asks whether you review that functionality at renewal or during planning, and notes that “vendors would prefer you do this at renewal” (4. Friedman, 2026).

At renewal you have a deadline, a rep who knows your account, and a price compared with last year’s contract instead of with the job. Each of those pushes you toward signing without a test.

Skipping the review only works when you know what you want

Sadoun limits his own point. He says going deep with a single partner works for clients “that know what they want” (1. Clarke, 2026). This team didn’t meet that condition.

The team knew the vendor well. What it lacked was a job specific enough to test. A testable job reads more like this: raise the share of marketing-qualified leads that sales accepts in our 2 largest segments, scored against the last 18 months of closed deals. With that sentence written down, the scoring module has something to beat.

What did the two-week proof show?

The skipped check explains the scoring results. Nobody had looked at the quality of the underlying data before the scores went live. When the team finally ran a two-week test on its own data, the rules-based lead scoring already built into the platform beat the AI module on the segments that mattered.

The add-on stayed on the invoice anyway, because removing it meant reopening the whole contract.

Tony Byrne, founder of analyst firm Real Story Group, advises clients to include “a hands-on bake-off between two finalists” in new purchases (5. Byrne, 2026). An upgrade has 2 finalists too. One is the upgrade, and the other is what you already own. This team didn’t put them side by side until months after it signed.

How to run a software proof of concept on an upgrade

Write the job in one sentence with a segment and a number. If you can’t, you’re not ready to buy the upgrade.

Run the test in your own instance, on your own records, against the feature you already pay for . If the upgrade can’t beat that feature, you don’t need the upgrade.

Name the people who’ll use it in the first month. If the list is shorter than the seat count, you’ve found part of your answer.

Ask for trial access 60 to 90 days before renewal, or ask for the upgrade as a separate line you can drop at 90 days. A proof does cost something. It takes a couple of weeks of your marketing ops team’s time, and pushing it past the renewal date can cost you a discount. For this team, a two-week test before signing would have shown the data and adoption problems before the $42,000 was committed.

Before your next renewal, list every line item added since the last contract. Next to each, write the job it was bought for and who used it this month. Any line with no job and no user is the first one to test before you renew it.