Microsoft’s TechNet program is one of the best bargains in personal computing. For an annual subscription price of $349, TechNet Professional subscribers get access to nearly every release of every operating system (desktop and server) and Office suite.

The licenses are valid for evaluation purposes only, but the downloadable products and product keys are typically Retail products, indistinguishable from shrink-wrapped products.

Two years ago, a TechNet Professional subscription entitled you to 10 product keys for every version of Windows and every version of Office. In September 2010, citing concerns over piracy, Microsoft cut those allotments to five keys.

Now, according to an announcement at the TechNet Subscriptions home page (link available only to signed-in TechNet subscribers), the number of product keys has just been slashed again:

Beginning in mid-March 2012, subscribers to TechNet Subscriptions (excluding TechNet Standard which are entitled to 2 keys per product) may access a maximum allocation of three (3) product keys for Microsoft Office and Windows Client products in connection with their subscription. The allotted keys may only be used for software evaluation purposes. Once the maximum keys have been activated, no more keys will be made available. Additional product keys may be acquired through the purchase of an additional subscription.

In addition to that restriction, Microsoft has also imposed restrictions on the number of keys that can be claimed on any given day. As another support page notes, a TechNet Professional (Retail) subscriber can claim 44 keys in a 24-hour period.

Reaching your limit means that you have claimed the maximum number of keys allowed for your program benefit level within a 24 hour period. Every 24 hours you may claim another set of keys, up to your program levels maximum.

The same document includes an explanation of sorts for the sudden spate of changes:

Why has Microsoft limited my access to product keys? We are acting to protect the value of your subscription. If we did not act to prevent abuse of subscriptions we would eventually have to either limit the products available in a subscription or raise the price of your subscription. We believe that this is the best compromise to continue to deliver the highest value to you while limiting abuse at the same time.

Over the past few years, I have encountered countless examples of unauthorized resellers hawking Windows and Office product keys on legit-looking websites. It was a lucrative business for scammers, whose $349 got them 10 licenses for Windows 7 Home Premium and Windows 7 Professional and Windows 7 Ultimate. It was practically a license to print money, as long as their customers activated the resold product keys before Microsoft cut them off.

Even at five keys per product, the economics made it worth trying.

The question now is whether the newly reduced allotment of product keys will actually reduce piracy or simply annoy TechNet subscribers.