Hello Mike,
Thanks for getting in touch with us.
In theory you can upload the plugins to your second site as well, however you will not be able to receive automatic updates for our premium plugins, so you would always need to do that manually and officially you will not be eligible for support for that site.
Here’s a post summarizing what support is provided for license holders.
Instead of repurchasing all the plugins, you also have the options to upgrade to a business license that grants you updates and support for 3 sites and costs $149 for Events Calendar PRO for example. If you upgrade from a single license then of course you only need to pay the difference. ($149 – $89 = $60)
I hope this explains. Let me know if you have any more questions.
Cheers,
Andras