Lots went wrong, I advise against using this company: 1) I purchased a licence key for office pro 2019 in March 2021. They only provide OEM keys that only work with telephone activation. I have no problem with this, except that it appears Microsoft only have an online registration system for Office 2019. 2) Therefore all instructions provided are incompatible and unhelpful. 3) I had five rounds with support to get this resolved, but they were consistently unhelpful. Each response was generic, took no account of the problem and ultimately has not resolved the issue. Despite providing screen shot and a clear explanation. 4) Ticket turnaround time was typically two days - So I've persevered for ten days, without resolution. 5) Final straw was CJS providing an alternate source file download on a google drive which was unavailable, as it violated google's terms. I completely appreciate Microsoft are taking financial advantage of their market power, but this is not a viable alternative. I suspect CLS's keys may work with office 2016 and earlier, but clearly they have not taken account of recent advancements by Microsoft for v2019. I've requested a refund and await response. CJS, if you're reading this, my ticket was #398559, you have work to do :)