I currently have Windows 10 on my bootcamp partition on the HDD of my iMac 2012. I want to transfer this to an External SSD (USB or Thunderbolt) but maybe not until after 29th July. As it was an upgrade from Windows 7 to 10, will I be able to do this after the 29th July or will I lose my eligibility? The thing that worries me is if i need to install 7 again will I be able get get back 10 again without paying?