Startups may take advantage of the BizSpark Graduation offer that allows startups to keep the software they have with the option to purchase subscriptions and maintenance if they want to keep it up to date. This also allows them to continue using their Microsoft software at no cost in perpetuity and allows them to renew subscriptions to this software without paying any initial license fees. Startups can:

•Keep their MSDN Ultimate software and optionally renew their MSDN subscriptions at any level

•Keep all their Windows and SQL Servers they are using in production and optionally purchase the first two years of Software Assurance (updates and ongoing maintenance) at a 50% discount

It's remarkably friendly although you could paint yourself into a corner if you went crazy with SQL Server, but there are a lot of options these days for dealing with large volumes of data.

At the end of 3 years the costs are hopefully going to be incidental.