'I therefore conclude that' is correct and usable in written English. You can use it to draw a conclusion based on evidence or facts that you have just presented. For example: After analyzing the data from the survey, I therefore conclude that most people prefer online shopping to shopping in physical stores.
I therefore conclude that these deficits are not a consequence of abnormal segregation of figure from background.
I therefore conclude that it is not the worst that political events bring out of people but their most private inner survival fears.
I therefore conclude that the DNA methyltransferase DNMT2 has no detectable effect on recombination in D. melanogaster.
I therefore conclude that legalization of settlement and subsistence activities are important not only for livelihood security and social cohesion of local inhabitants, but possibly also for biodiversity conservation.
I therefore concluded that it was my task to be extraordinary, which I then sought to carry out as best I could.
I therefore concluded that the author of the email deserves the label "antisemite" just as much as Stone does.
We may therefore conclude that is -holomorphic.
Being a terminologist, I care about word choice. Ludwig simply helps me pick the best words for any translation. Five stars!
Maria Pia Montoro
Terminologist and Q/A Analyst @ Translation Centre for the Bodies of the European Union