The free spin is given for reading the daily email from the site, thats why it expires after only after a short leeway of a day or so. You might want to click refresh in case its an error for a moment, I get that occasionally and it works after. The other thing I do because I get so many emails is I use a filter on gmail to catch this particular email, star it and then forward it back to myself so it definitely arrives 1pm every day and I will see it. I imagine the site layers their email sending so the time of arrival for some will vary and of course globally everyone's time is different, in short you could easily miss and lose this deadline opportunity to claim.
Just a single spin isnt massive but collectively over a year 365 spins definitely amounts to something worth having, also I like the technical price analysis they send out sometimes etc.
It sounds like you have found a way to make sure you don't miss out on the daily free spin by using filters and forwarding the email to yourself. That's a good tip for anyone who wants to make sure they don't miss out on the opportunity. It's also good to keep in mind that even though a single spin may not seem like much, the cumulative effect of getting a free spin every day for a year can add up. It's always worth taking advantage of opportunities like these when they are available.