Hey Mohamed,
Thanks for reaching out. Stoked to hear you’re considering packaging The Events Calendar in your theme — that’s awesome!
You are certainly welcome to package PRO in there as well and use an Unlimited level license. However, please note that it only allows you access to support here in these forums, rather than each of your customers. That said, you may want to consider the support implication and what it would look like for you to support The Events Calendar and Events Calendar PRO for your customers. My biggest concern, at least from our end, is that customers experiencing issues with PRO would want to reach out directly to us, but not have the access to do so under that arrangement — that could be a source of frustration and confusion.
It also would require you to share your license key with every customer. The license key is needed to enable automatic updates in WordPress and, without it, customers will see a notification that an update for PRO is available but will be unable to install it. You’re totally welcome to give your license key to customers, but that is something I wouldn’t exactly recommend doing.
Does this help answer your question? Please let me know and I’d be happy to help as best I can.
Cheers!
Geoff