Are keys bought from third party sites like G2a.com or Kinguin accepted?

just my opinion here and i do understand the hesitation though but personally  i prefer to buy from reputable sites such as amazon and or origin   just keep an eye out for a sale on origin  just do not buy used/2nd hand ones as the code will be no good to you as it will be tied to the original owners account

i'm tagging a CM to see their opinion on this as i'm not familiar with those sites  and they may or may not be endorsed by EA  as a seller

@EA_Nils  or @EA_David  any input here please and thank you in advance