> We're updating products that are 3+ years old without asking our existing users for one extra dollar.

Obviously, you're the expert here, but wouldn't you consider rolling that service into your subscription package and increasing the number of subscribers a bit.

I don't think any customer even expects you to give them free updates on stuff they bought more than 3 years ago, 'lifetime' free updates are really friendly but it sounds like money left on the floor.

Of course it's excellent PR, and if there is no potential upside to doing this differently then kudos to you for being so friendly to your customers.