Yes, the strategy for big client is to lock them in for long engagement (like a 3-YR term). Throw in some nice support package, longer trial period, whatever. Since big customers often take months to fully use a product (6-12 months is very common), I wouldn't worry about "oh now I got big name, I need more infrastructure, more money to pay my cloud vendor." It won't for 6-12 months and you probably can keep all the pennies from the big client monthly. If you get a downpayment (say 1-year for a 3-yr term), you get ammunition to grow your team and get more smaller customers.