My seating planner software, PerfectTablePlan, is now at v7. Major upgrades are paid (discounted 60% compared to new licences), which means I have done 6 cycles of paid upgrades. I was curious about how long it took people to upgrade, and what percentage of sales are upgrades. So I took a few minutes to crunch the numbers direct from my licence key database, using my data wrangling software, Easy Data Transform.

Here are the number of upgrade licences I sold for each week after the major upgrade. Each release is in a different colour. The values are normalised so that the peak is the same height for each release:

That looks rather messy. So here it is with the values for the 6 upgrades summed:

There is a long tail of upgrades. Even when the gap between releases was 6 years, I was still getting regular upgrade purchases.

With the v5 to v6 upgrade it took:

• 23 weeks before 50% of the upgrades were sold.

• 74 weeks before 75% of the upgrades were sold.

So it isn’t a neat exponential decay.

This table shows how many users actually upgraded from v5 to v6:

Edition	Upgraded
Home edition	12%
Advanced edition	31%
Professional edition	45%

Most of the Home edition purchasers are buying a licence for a one-off event, such as a wedding. So it is not surprising that they are much less likely to upgrade. But I think it also shows that less price-sensitive customers are significantly more likely to upgrade, even when the upgrade is more expensive.

This graph show the percentage of PerfectTablePlan licences sold each month that were upgrades, over the 20 year life of the product:

You can see that upgrades are still increasingly important over time. Upgrades are worth less than new sales, so selling 80% upgrade licences in a month doesn’t mean 80% of revenue is from upgrades. However, upgrades are still an increasingly significant source of revenue for us. I’m glad I never agree to free upgrades for life.

Could I have made more sales with more frequent major upgrades? Definitely. But I was also working on other projects. And I am not out to squeeze every last penny out of my loyal customers.

Could I have made more sales with a subscription model? Possibly. But subscriptions weren’t really a thing for desktop software, when I started 20 years ago. And I never felt like making a major change to a licensing model that had worked well for me, so far.