Looks like he is requiring the support plan before letting you download the new update which is a good thing in my opinion. That should clear up confusion as there are tons of posts where people updated out of support only to find their BI installation reverted to Eval mode and they didn't know why.
No, you dont HAVE to pay 30 bux a year. You MAY.
Microsoft does do that. They charged for yearly updates, they just used a sneaky trick. You see, they charged 100-150 for windows, then forced you to upgrade every few years to a "new version". Microsoft also has a vested interest in keeping as many people as possible running their os and keeping the os secure even if they lose money on some. Look at any specialty software, quickbooks, graphic design etc all have these type of costs, however they are much higher than the measly $35 bux BI is charging.
Would it make you feel better if every year he added a version number, 5,6,7,8 or charged you 100 bux at the outset? Blue iris is all about options, one of those options is the ability to get new features via updates. You dont HAVE to do it if 35 bux will leave you homeless - however in that case you likely dont need BI.
Most vms - many with WAY less useful features charge PER camera and have yearly update and support fees. The only vms I am aware of that provides FREE lifetime updates and UPGRADES is nxwitness (sold as DW ipvms in north america) and their licensing is 70 bux per camera.