IANAL, and no tax advisor neither. The following are bits and pieces of knowledge picked up as freelancer and business owner located in Germany.
I'm going to read "individual" as private individual, so a B2C contract (as opposed to the owner of a business that is not considered separate from the individual - which would be a B2B situation and very different in terms of VAT).
does the individual that purchases the service have to pay any taxes or
social security contributions
Iff the freelancer is properly set up as business they are responsible for their social security themselves.
Where to really find out? (Don't trust random strangers on the internet...)
(or in general any other fiscal, legal, or bureaucratic responsibilities)?
I've made good experience with asking my tax office whether there's anything special I need to be aware of in terms of taxes/whether I have to report something and which form as I'm in the following situation ... . They are usually friendly and helpful nowadays as long as you don't ask them for advise on how to avoid taxes.
When buying a software license from outside the EU, my experience with asking customs is medium-good: they told me that as my license was provided over the internet (as opposed to a CD being shipped), customs is not involved at all (correct) and that I don't need to do anything special (that part missed said §50a EStG).
Conclusion: customs can probably correctly tell you about what is their concern (import/export of goods and black work would be the relevant in the context of this question), but not necessarily about tax-related specialties. So maybe ask the tax office as well.
BTW: my tax advisor had missed that §50a as well...