Three questions narrow this down quickly.
First: do you already know you’ll be diagnosing WordPress problems regularly, or are you testing Loupely for the first time? If you’re not sure yet, start with credits. The 10-credit pack at $19 gives you 10 diagnoses to see how useful Loupely is for your situation before you commit to a year. Credits don’t expire, so there’s no pressure to use them quickly.
Second: how often will you actually run diagnoses? Loupely Annual costs $99/year and gives you unlimited Loupely diagnoses for 12 months. At the credit rate of $1.90 each, the break-even point is around 53 diagnoses in a year, roughly 1 per week. If you’re managing a WordPress site that has problems occasionally, once or twice a month, credits are probably more economical. If you’re maintaining multiple sites or running into problems regularly, the annual plan pays for itself fast.
Third: do you also need Loupely Lens for CSS visual problems? Loupely and Lens are separate products with separate annual plans, but they share one account and one credit pool. The Bundle Annual at $119/year covers both products with unlimited diagnoses, which saves $9 over buying both separately. If you know you’ll use both, that’s the math.
The Agency plan is not currently available at launch. It will be added after client-deliverable infrastructure is built.
If you’re still unsure: credits, no commitment, see what you actually use.