There will be any number of security products available to provide a level of protection on a W7 installation, even though it will no longer be supported by Microsoft; e.g. Avast, AVG, MalwareBytes etc. These are likely to continue with their support for W7, as they are still able to make money out of it.
If however you'd like to update to W10, even though the free period has supposedly expired, I pointed a friend to this method a few months ago. I saw him the other day, when he confirmed all was still OK
Depending on whether this is your main PC or a secondary one, and how much you want to play, it should be possible to come up with a dual boot system of W7 + W10
One method which springs to mind, although slightly convoluted.
Make a full system image of your W7 installation; probably not a bad idea anyway.
upgrade to W10 using the method I linked to earlier.
Use Nirsoft Produkey to find the new W10 COA number, which will now be registered with Microsoft legitimately
Restore your W7 image, and download W10 as a normal bootable ISO, installing it as dual boot; when it asks for the registration number, use the one you previously extracted via Nirsoft.
Another possibility, and I don't know if it would work, is after the upgrade, you used to get something like 30 days to reject it and continue with your earlier Windows install.
Extract new W10 COA number using Nirsoft, reject W10, as you seem to have done previously, and then download the W10 installation USB image.
Install as dual boot, again inputting the Nirsoft extracted number for registration.
Bill