I was wondering if we need to pay for a license for our partner to use within BC? We have 24 users but one of these was set for our partner during the migration to BC and it is still there - is this normal practice or after the migration was completed should this have been released for us to use for any new employees?
In addition, if your environment was created in a third-party Partner Center and is not the supported partner, you must purchase an additional license because the partner cannot log in with a delegated admin.
I've come across partners who create customer environments in their Partner Center to allow customers to receive discounts on AppSource extensions. . . .
If your partner is a Microsoft partner they can access your Business Central environment as a delegated admin, meaning they do not require a Business Central license to do the implementation or provide support. You would not need to buy a Business Central license for them. This requires you to give them access as a delegated admin. But its very simple for your partner to set this up.
However, I did come across some partners who do not know about this so they ask the customer to buy a license for them. There are also certain things that are not possible to do with delegated admin access and a Business Central license would be required. So it really depends on the scope of the implementation, and what they're currently helping you with. However, I would say 95%+ of the time a Business Central license is not required for neither the implementation nor to provide support, and delegated admin access is enough. I would ask your partner to confirm why they need a license now and during the implementation. Perhaps they are helping you with something where delegated admin access is not enough.
For example, most of the clients I help do not buy me a Business Central license as I access their environments as a delegated admin as there's no reason for them to pay an extra $1000+/year when I can get access for free. However, some clients bought me a license as I help them with Power BI or Power Apps in addition to Business Central where delegated admin access would not be enough.