I want to migrate my data from 3DCart site to a Shopify site
I will have 301 redirects created during the migration process.
When the migration is done and I'm ready to launch my new Shopify site can I cancel my old 3D cart site? OR does that cause you to lose these "301 redirects" that were set up?
I'm unfamiliar with this process and I can't afford to pay for an old shopping cart that I wont be using (at close to $400 a month) when I will have a whole new Shopify cart.
Is the domain you are going to use on Shopify different from the one you have used for your 3DCart website?
In this case, the operation is simple, you just need to create the redirects manually inside the Shopify backend.
Could be quite laborious tough, because Shopify doesn't accept complex redirect rules (using regex for example).
But you can describe the redirects in a CSV file and import that in Shopify.
301 is a permanently moved status code which means it'll moved entirely your old site to the new URL and the old site now will be dead. Therefore, the answer is YES, you can cancel your old site on 3DCart after creating 301 redirect and it won't affect your new site.
In case you need an automated tool to migrate your shopping cart from 3DCart to Shopify, I'd highly recommend LitExtension for its accuracy, high data security, and great support.
Hope that my answer will be helpful to you. Have a nice day!