Password on different platforms or do I have to buy again

Hello Paul.
We'd be glad to answer this if you could clarify which AVG product are you planning to purchase.

if I buy license for pc, can I then convert that or get some discount to install on my Mac laptop, or do I have to buy it all again.

I have already brought tuneup for the pc, and want to install on my Mac laptop

Paul, you do not have an active subscription for AVG TuneUp registered to the email address that you used to contact us here.
I have sent an email requesting more details to locate this order. Please revert it containing those details.

Hello Paul.
We'd be glad to answer this if you could clarify which AVG product are you planning to purchase.